The process of fractional crystallization cannot create a felsic magma from a melt that was originally mafic in composition.

Answer 1

"Cannot" is a bit strong here. More strictly, I'd say a mafic magma cannot create very much felsic magma from the process of fractional crystallization. Under just the right circumstances and series of magma exchanges, I'd say it is possible to create a felsic magma in this way, but not very much of it, and it's not very likely. Fractional crystallization of a mafic magma will generate a magma that is less mafic than before, possibly not even truly intermediate at first go. To get a good amount of felsic magma in this way, we'd need to start with an intermediate source magma, or even a magma a bit more felsic than that.