Transgender isn't a sexual orientation. You can be transgender as well as straight, gay, bi, asexual, whatever. It's inward focused, about who you feel you are, not outward, about whose genitals you want to play with. Say someone is a trans woman - meaning she was born a man but is female, maybe even had sexual reassignment surgery. You can't assume what she's into. She could be into men, and we'd then say she's straight. She could be into women, and we'd say she's gay. She could be into both, neither, whatever.
As for the options... it's complicated. But I think the majority of people would be comfortable choosing from between Heterosexual, Homosexual, Bisexual, and Asexual. There's a range in all of them... there are asexual people who crave physical contact, cuddling, foreplay even, but don't enjoy actually go all the way. There are straight guys who would put it in anyone's mouth and have no sexual identity crisis about it. There are gay guys who are exclusively top or bottom with no exception. And bisexuality is always pretty complicated in terms of how much it differs between people.
In any event, I'm gay.
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