People- J, K, L, M, N, O, P, Q and R.

Months: April, August and November.

Dates: 3, 11 and 24.

In a same month three people attend the seminar but on different dates.

Steps:

1) O attends the seminar on 3^rd August. Four people attend the seminar between O and L.

So, L attends the seminar on 24^th November.

2) Q attends seminars on an even-numbered date and in a month having an even number of days.

So, Q attends a seminar on 24^th April.

3) As many people attend the seminar after P as many attend the seminar before Q.

So, P attends the seminar on 3^rd November.

4) Four people attend a seminar between N and K where N attends the seminar before K.

So, N attends the seminar on 3^rd April and K attends the seminar on 24^th August.

5) R attends the seminar in august.

Means R attends seminar on 11^th August.

6) M attends the seminar on one of the dates after K.

So, M attends the seminar on 11^th November.

Thus, it is clear that J attends the seminar on 11^th April.

Hence, K attends the seminar on 24^th August.

People- J, K, L, M, N, O, P, Q and R.

Months: April, August and November.

Dates: 3, 11 and 24.

In a same month three people attend the seminar but on different dates.

Steps:

1) O attends the seminar on 3^rd August. Four people attend the seminar between O and L.

So, L attends the seminar on 24^th November.

2) Q attends seminars on an even-numbered date and in a month having an even number of days.

So, Q attends a seminar on 24^th April.

3) As many people attend the seminar after P as many attend the seminar before Q.

So, P attends the seminar on 3^rd November.

4) Four people attend a seminar between N and K where N attends the seminar before K.

So, N attends the seminar on 3^rd April and K attends the seminar on 24^th August.

5) R attends the seminar in august.

Means R attends seminar on 11^th August.

6) M attends the seminar on one of the dates after K.

So, M attends the seminar on 11^th November.

Thus, it is clear that J attends the seminar on 11^th April.

Hence, 1 person attends the seminar before J.

People- J, K, L, M, N, O, P, Q and R.

Months: April, August and November.

Dates: 3, 11 and 24.

In a same month three people attend the seminar but on different dates.

Steps:

1) O attends the seminar on 3^rd August. Four people attend the seminar between O and L.

So, L attends the seminar on 24^th November.

2) Q attends seminars on an even-numbered date and in a month having an even number of days.

So, Q attends a seminar on 24^th April.

3) As many people attend the seminar after P as many attend the seminar before Q.

So, P attends the seminar on 3^rd November.

4) Four people attend a seminar between N and K where N attends the seminar before K.

So, N attends the seminar on 3^rd April and K attends the seminar on 24^th August.

5) R attends the seminar in august.

Means R attends seminar on 11^th August.

6) M attends the seminar on one of the dates after K.

So, M attends the seminar on 11^th November.

Thus, it is clear that J attends the seminar on 11^th April.

Hence, both N and Q attend the seminar in April.

People- J, K, L, M, N, O, P, Q and R.

Months: April, August and November.

Dates: 3, 11 and 24.

In a same month three people attend the seminar but on different dates.

Steps:

1) O attends the seminar on 3^rd August. Four people attend the seminar between O and L.

So, L attends the seminar on 24^th November.

2) Q attends seminars on an even-numbered date and in a month having an even number of days.

So, Q attends a seminar on 24^th April.

3) As many people attend the seminar after P as many attend the seminar before Q.

So, P attends the seminar on 3^rd November.

4) Four people attend a seminar between N and K where N attends the seminar before K.

So, N attends the seminar on 3^rd April and K attends the seminar on 24^th August.

5) R attends the seminar in august.

Means R attends seminar on 11^th August.

6) M attends the seminar on one of the dates after K.

So, M attends the seminar on 11^th November.

Thus, it is clear that J attends the seminar on 11^th April.

Hence, 4 people attend the seminar between J and P.

People- J, K, L, M, N, O, P, Q and R.

Months: April, August and November.

Dates: 3, 11 and 24.

In a same month three people attend the seminar but on different dates.

Steps:

1) O attends the seminar on 3^rd August. Four people attend the seminar between O and L.

So, L attends the seminar on 24^th November.

2) Q attends seminars on an even-numbered date and in a month having an even number of days.

So, Q attends a seminar on 24^th April.

3) As many people attend the seminar after P as many attend the seminar before Q.

So, P attends the seminar on 3^rd November.

4) Four people attend a seminar between N and K where N attends the seminar before K.

So, N attends the seminar on 3^rd April and K attends the seminar on 24^th August.

5) R attends the seminar in august.

Means R attends seminar on 11^th August.

6) M attends the seminar on one of the dates after K.

So, M attends the seminar on 11^th November.

Thus, it is clear that J attends the seminar on 11^th April.

Hence, ‘L-November’ is correct combination.