Each letter in the given series is multiplied with 2 to get the next letter in the series.

A = 1 and 1 × 2 = 2 and the 2nd letter is B.
B = 2 and 2 × 2 = 4 and the 4th letter is D.
Similarly, H = 8 and 8 × 2 = 16, and the 16th letter P is the missing letter.

So, Correct Option is Option A

D, F, G, H, J, K, L, M, N, ____

The given series consists of consonants in increasing order, starting with D.
The next consonant in the series is P.

So, Correct Option is Option B

G + 3, J + 4, N + 3, Q + 4, U + 3 , _____
The next letter in the series is U + 3 = X.

So, Correct Option is Option C.

BY, CX, EV, GT, KP, _____

The given series is a mixed series.

• The letters B, C, E, G, and K are the letters in prime value positions. Hence, the next letter is M.
• The second letter in each group forms an opposite pair of the first letter in that group. Hence, the next pair in the series is MN.

• The first letters in all the pairs, i.e., A, B, C, and D, form a series of consecutive letters.
• The second letters P, Q, R, and S form another pair of consecutive letters. Hence, The next pair in the series is ET.

• The first letters in all the groups are consecutive vowels starting with A.
• The second letters in all the groups are consecutive vowels starting with I.

Hence, the missing pair is OA.

The given series is a mixed series.

• Pattern for the first letter:
  K + 1, L + 1, M + 1, N + 1, O
• Pattern for the second letter:
  P – 1, O – 1, N – 1, M – 1, L
• Pattern for the third letter:
  D + 1, E + 1, F + 1, G + 1, H
• Hence, the next group in the series is OLH.

The alternate groups are in mixed series.
QLR, RNU, SPX are in one series.

• The Pattern for the first letter:
  Q + 1, R + 1, S + 1, T
• The Pattern for the second letter:
  L + 2, N + 2, P + 2, R
• The Pattern for the third letter:
  R + 3, U + 3, X + 3, A

Hence, the next group in the series is TRA.

The given series is a mixed series.

• Pattern for the first letter:
  G – 4, C – 4, Y – 4, U – 4, Q
• Pattern for the second letter:
  T + 5, Y + 5, D + 5, I + 5, N
• Pattern for the third letter:
  B – 6, V – 6, P – 6, J – 6, D

Hence, the missing group is UIJ.

• In each term the numbers are pairs of consecutive prime numbers.
• The letter between them has the place value equal to the product of the two numbers on either side of it.

∵ The next two prime numbers are 11 and 13 whose product is 143. The 143rd letter is (26 × 5 + 13) M.
∴ 11M13 is the next term.

When the letters are reversed in the group of Five, six, and seven letters.
5th to the left of 12^th from the right end (27- 12 = 15^th from left) means, 15 – 5 = 10^th that lies in the 2^ndgroup(6-11).
Therefore, 6 + 11 = 17 – 10 = 7^th letter i.e. “G”.

When the letters are reversed in the group of Five, six, seven and letters.
5th to the right of 12th from right end (27 – 12 = 15th from left) means, 15 + 5 = 20th
Which lies in 4th group(19-26). Therefore,
19 + 26 = 45 ; 45 – 20 = 25th = “Y”.