Who Among the Following Is Most Likely Straight

Who among the following is most likely straight?

A) Perry, a woman in her forties who has been dating Sarah, a young woman, for two years
B) Helen, a young woman who enjoys sexual intimacy with both men and women
C) Kate, a woman who is sexually attracted to her female colleague Veronica
D) Ricky, a man in his fifties who is sexually attracted only to young women