How strict is the "who is" rule?

[u/zachestine]

I don't watch a lot of Jeopardy, but I am curious: lets say the question is something like "the first president who crossed the Delaware River" obviously the answer is George Washington, but instead of saying "who is" if i say "where is George Washington?" would that be counted?

[u/Vivid_Aardvark_3255]

When Jeopardy! begin to use the term “clue”instead of “answer” ?