What Do Researchers Believe Is a Possible Mechanism for Gender

What do researchers believe is a possible mechanism for gender dissatisfaction?

A) an allele of the CYP17 gene that increases testosterone in female-to-male transsexuals and thus leads to failed masculinization of the male brain
B) an allele of the CYP17 gene that increases testosterone in female-to-male transsexuals and thus leads to masculinization of the female brain
C) an allele of the AR gene that increases testosterone in female-to-male transsexuals and thus leads to failed masculinization of the male brain
D) an allele of the AR gene that reduces sensitivity to androgen in male-to-female transsexuals and thus leads to masculinization of the female brain