"a) and d)"

Well, wofa, my newNuncle Fal has produced a cogent summary of why (d) is the only correct answer. However, that's "by the book" (M-W in this case).

(a) -- a namesake is the (more) original person with the name -- was my first response when asked, as it appears to have been yours, your secretary's and TEd's. Oh, and Auntie Elizabeth Fischhoek's. That's enough people in a small sample for me to judge this a common usage, and therefore a reasonably valid meaning. (d) remains the primary meaning, of course.

So, wofa, I'll have a quick flashback to my days reading Marvel comics, and award you a No-Prize. Congratulations!

Incidentally, my wife went for (b) as first choice - hence this thread. And the phrase that kicked it off was on a recent Elvis special on UK TV in which I think Elvis Costello was called the King's "namesake".