Can be (and is) used two ways:
1: the person for whom a child was named (doesn't have to be a parent)
2: either or both of two people with the same name ("We are namesakes!")

I think that makes my answer "a) and d)".

And I just asked my secretary what it meant and she gave me that exact answer, independently. So it must be true!

Humpty-Dumpty would be pleased. "When I use a word, it means exactly what I want it to, no more and no less." (or words to that effect) -- Lewis Carroll