Discuss the difference in visibility between a person's race and a person's sexual orientation and how it relates to discrimination.
Nothing of what you claim is in my post.  Nothing.  A black person is obviously black to all casual observers.  Not always, but the vast majority of the time.  This fact does not apply to homosexual people.  When a bisexual person engages in homosexual activity, does this make them homosexual or do they continue to be bi?  My point is that, really, it is none of my, nor your, business.  Unless you observe the activity, or if they proclaim their sexual preferences, you have no way of discriminating against the person.  Black Americans do not have this ability to hide their status.