As stated in the passage that the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), combines autism and less severe forms of the condition, including Asperger syndrome and pervasive developmental disorder not otherwise specified (PDD-NOS) into the diagnosis of autism spectrum disorder (ASD). Hence, option C is the correct answer.

As stated in the passage that the number of people diagnosed has increased dramatically since the 1960s, which may be partly due to changes in diagnostic practice. Hence, option B is the correct answer.

As stated in the passage autism is a developmental disorder characterized by difficulties with social interaction and communication, and by restricted and repetitive behavior. Hence, option C is the correct answer.

As stated in the passage that globally, autism is estimated to affect 24.8 million people as of 2015. In the 2000s, the number of people affected was estimated at 1–2 per 1,000 people worldwide. In the developed countries, about 1.5% of children are diagnosed with ASD as of 2017, from 0.7% in 2000 in the United States. Hence, option A is the correct answer.

As stated in the passage that parents often notice signs during the first three years of their child's life. These signs often develop gradually, though some children with autism experience worsening in their communication and social skills after reaching developmental milestones at a normal pace. Hence, option D is the correct answer.

As stated from the passage options A, B and D are correct, there is no proof that autism can be cured through extensive physical therapy. Hence, option C is the correct answer.

Let us understand their meanings-

Dissension- disagreement that leads to discord or difference of opinions

Controversy- prolonged public disagreement or heated discussion

Forbearance- patient self-control; restraint and tolerance

Felicity- Intense happiness

Solace- comfort or consolation in a time of great distress or sadness

Here the only possible synonym for dissension can be controversy. Hence, option A is the correct answer.

Let us understand their meanings-

Consort- habitually associate with someone or something

Clump- a small group of trees or plants growing closely together

Boodle- money especially that gained or spent illegally or improperly

Segregate- set apart from the rest or from each other; isolate or divide

The only possible antonym for consort here can be segregate. Hence, option D is the correct answer.

The passage is a part of summary of an article on autism; this can be deduced by eliminating the options. As option D and B are out rightly eliminated and option A can be a likely answer but is also eliminated because option C fits the format of the passage (what, how, where). Hence, option C is the correct answer.

As stated in the passage that autism is a highly variable, neurodevelopment disorder whose symptoms first appear during infancy or childhood, and generally follows a steady course without remission. Hence, option B is the correct answer.