US Constitution provides for a federal government superior to state governments in regard to enumerated powers. Federal law trumps any state law in explicit conflict. State law subservient to federal law in case of explicit conflict. If state law affords more rights to residents, the state law is presumed to prevail.
D.
I believe is the answer
Hope this helps, sorry if not tho
I think it was because we really don't know what exactly happened in the past.
Also, I'm pretty sure people did not keep track of colored people back then.