Which of the Children Below Is Most at Risk for Physical

Which of the children below is most at risk for physical abuse (based on epidemiological studies) ?

A) 14-year-old, Bob, who lives with both his mother and his father in a middle-class neighborhood
B) 8-year-old, Amy, who has adequate intelligence and lives with her single mother
C) 6-year-old, Jim, who has an IQ of approximately 40 due to Downs Syndrome
D) 11-year-old, Ray, who lives with his caretaking grandmother