What is true of a gay man's or lesbian's right to adopt in the U.S.?

What is true of a gay man's or lesbian's right to adopt in the U.S.?
 
  a. Adoption is illegal for gays and lesbians in all of the states of the U.S.
  b. Adoption is legal for gays and lesbians in all of the states of the U.S.
  c. Adoption is legal for gays and lesbians in many states in the U.S., and for all of the states where it is legal, both parents from a same-sex relationship can establish themselves as the legal parents.
  d. Adoption is legal for gays and lesbians in many states in the U.S., but only a few states allow both parents from a same-sex relationship to establish themselves as the legal parents.