Jerry Was Born with a Round Face,flattened Skull,short Limbs,and Retardation

Multiple Choice

Jerry was born with a round face,flattened skull,short limbs,and retardation of motor and mental abilities.The doctors told Jerry's parents that this is because he has an extra copy of chromosome 21.Which of the following chromosomal abnormalities does Jerry have?

A) phenylketonuria
B) Turner syndrome
C) sickle-cell anemia
D) Down syndrome