Which statement about the prevalence of intellectual disability is true?

• A. It is the most common developmental disability
• B. It is always accompanied by multiple disabilities
• C. It never requires sped services
• D. It affects only a small fraction of children

Answer: (C)

Prevalence asks how common something is in the population. Intellectual disability affects about 1% of children, so it’s a relatively small fraction. That makes the statement about prevalence that it affects only a small fraction true. The other points mix in service needs or comorbidity rather than prevalence: it isn’t necessarily the most common developmental disability, it isn’t always accompanied by multiple disabilities, and many students with intellectual disability do require special education services. So the accurate takeaway about prevalence is that it affects a small fraction of children.