I was on the receiving end of this question, and as someone who got a fairly decent mark in Latin 'O' Level, not to mention Physics 'A' Level (albeit some time ago now) I was disappointed not to get it right.
My defence is that I was put off by the reference to "equation".
In my mind, the word "quantum" is associated with "theory" or "mechanics" – not "equation".
Apparently, physicists don't talk about "quantum theory" any more; Wikipedia does have a Quantum theory page, but this just refers you to various other pages (including "old quantum theory", which is described as "predating modern quantum mechanics").
If you google "quantum equation", the first hit you get is to Wikipedia's page for the Schrodinger equation (whatever that is, I might add). The next is Wikipedia's List of equations in quantum mechanics page; and the next (apart from Images for quantum equation) is a page entitled Quantum Mechanics on a website called Physics for Idiots.
Like I said: the word "quantum" is more associated with the word "mechanics" than "equation". (Or, in my mind at least, "theory".)
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