Dennis is a 17-year-old who comes to a counselor because he feels sexually attracted to males, which is at odds with his religious beliefs. Although he has felt this way for a long time, he is still struggling to understand why? Based upon the information presented, which of these explanations has some research support?

a. Homosexual orientation usually results from being reared by a parent or parents of the same sex.
b. Homosexual orientation results from being exposed to early sexual abuse.
c. Homosexual orientation is at least partly determined by heredity.
d. Homosexual orientation is a personal choice made by the individual.