Final answer:
The symptoms of Autism Spectrum Disorder usually occur before the age of 3 years old.
Step-by-step explanation:
The symptoms of Autism Spectrum Disorder usually occur before the age of 3 years old. Autism is a neurodevelopmental disorder that affects social interaction, communication, and behavior. Some common symptoms include impaired social skills, difficulty making eye contact, repetitive behaviors, and preoccupation with specific subjects.