Marvin Is a Second Grade Student with a Moderate Intellectual

Marvin is a second grade student with a moderate intellectual disability. His teachers claim that his gnome costume for Halloween was perfect for him. They say that he is always happy and that he never meets a stranger. Recently his teacher had to stop him from leaving the classroom with a man who had come to fix the computer. Marvin displays characteristics of a person with _____.

A) PKU
B) fragile X syndrome
C) Prader-Willi syndrome
D) Williams syndrome