Which of the following statements regarding autism is correct?

• A. The majority of patients with autism do not speak at all.
• B. Impairment of motor activity is a classic sign of autism.
• C. Most cases of autism are diagnosed by 3 years of age.
• D. Autism affects females four times greater than males.

Answer: (C)

Autism spectrum disorder is typically identified in early childhood, with most cases diagnosed by age three. By this age, patterns of persistent social communication deficits and restricted, repetitive behaviors become clear enough for a clinician to evaluate and diagnose, often after initial screening at around 18–24 months and a thorough follow-up if concerns remain. This timing is why stating that most cases are diagnosed by age three is the best answer: it reflects common clinical practice and the point at which formal assessment can reliably occur to guide early intervention.

Language development in autism is variable, so saying the majority do not speak at all isn’t accurate—many children on the spectrum do develop speech, though they may show atypical patterns or delays. Impairment of motor activity isn’t a defining feature; motor difficulties can occur but are not part of the core diagnostic criteria. And while autism is more common in males, the correct statistic is that it occurs more frequently in males (roughly four times as often as in females), not the other way around.