Retrospective Studies Looking at the Development of Sexual Orientation

Retrospective studies looking at the development of sexual orientation:

A) have consistently found that the development of male or female homosexuality is almost always due to an early and unpleasant childhood experience with a member of the opposite sex.
B) are seriously flawed because parents often engage in the "halo effect" and only report positive experiences about their children.
C) may be biased by what the participants recall about childhood events.
D) are regarded as the only reliable way to get an accurate understanding of the factors that influence a person's sexual development.