Why Were the Results on Homosexual Behavior That Were Obtained

Why were the results on homosexual behavior that were obtained from studies with control groups unreliable?

A) The investigators assumed that homosexuality is an innate instinct of every being which is usually suppressed in normal people by puberty.
B) The investigators began with the premise that homosexual behavior is normal and not connected to any psychological illness.
C) The investigators studied only men and not women,thus excluding half the population.
D) The investigators compared homosexuals in therapy to heterosexuals not in therapy,thus skewing their results.