According to Family,twin,and Adoption Studies,a Person Is at Greatest Risk

According to family,twin,and adoption studies,a person is at greatest risk for developing schizophrenia _________.

A) if he or she has an identical twin diagnosed with the disorder
B) if he or she has a nonidentical twin diagnosed with the disorder
C) if he or she has an adoptive parent diagnosed with the disorder
D) if he or she has a biological parent diagnosed with the disorder