The Issue of Classifying People's Sexual Orientations Is Made Difficult

The issue of classifying people's sexual orientations is made difficult by the fact that:

A) there are substantially more people who self-identify as homosexual than as bisexual.
B) homosexuals and bisexuals constitute such a small proportion of the population and there is an identification stigma.
C) there are substantially more people who self-identify as bisexual than as homosexual.
D) a relatively high percentage of people report same-gender attraction, yet do not identify themselves as homosexual or bisexual.