Which describes characteristics most consistent with autism spectrum disorder (ASD)?

• A. A four-year-old child who speaks in full sentences
• B. A three-year-old child who exhibits restrictive and repetitive patterns of behavior
• C. A two-year-old with advanced vocabulary
• D. A five-year-old who has tantrums only

Answer: (B)

Recognizing ASD features in early childhood involves persistent differences in social communication and interaction, combined with restricted and repetitive patterns of behavior, interests, or activities that appear early and can interfere with daily functioning.

The description of a three-year-old who exhibits restrictive and repetitive patterns fits this profile, since those rigid routines, repetitive actions, and focused interests are hallmark features often seen in autism spectrum disorder when children are very young.

The other descriptions don’t illustrate that combination. Speaking in full sentences at four can be typical language development for many children. Having advanced vocabulary at two could be impressive but doesn't by itself indicate ASD. A five-year-old with tantrums only doesn’t demonstrate the social-communication deficits paired with restricted behaviors that ASD encompasses.