Michael and Michelle Are Adolescents Who Share the Same Birthday

Michael and Michelle are adolescents who share the same birthday. Michael received a diagnosis of bipolar disorder. On the other hand, Michelle shows no signs of mood disturbance. In this example:

A) Michael and Michelle are most likely monozygotic twins, but Michael is genetically predisposed to develop a mood disorder.
B) Michael and Michelle are most likely dizygotic twins, but Michael developed the disorder because he modeled behaviors of other family members.
C) Michael and Michelle are most likely dizygotic twins, but Michelle did not develop the disorder because the concordance rate for dizygotic twins is usually low.
D) Michael and Michelle are most likely monozygotic twins, but Michelle did not develop the disorder because she has a higher tolerance for stress.