In Mammals, Individuals with Two X Chromosomes Are Female, and Individuals

In mammals, individuals with two X chromosomes are female, and individuals with an X and a Y chromosome are male.It had long been known that a gene located on the Y chromosome was sufficient to induce the gonads to form testes, which is the main male-determining factor in development, and researchers sought the product of this gene, the so-called testes-determining factor (TDF) .For several years, the TDF was incorrectly thought to be a zinc finger protein encoded by a gene called BoY.Which of the following observations would most strongly suggest that BoY might NOT be the TDF?

A) Some XY individuals that develop into females have mutations in a different gene, SRY, but are normal at BoY.
B) BoY is not expressed in the adult male testes.
C) Expression of BoY in adult females does not masculinize them.
D) A few of the genes that are known to be expressed only in the testes have binding sites for the BoY protein in their upstream regulatory sequences, but most do not.