“You have 3 12-hours clocks. One gains a minute every day, one loses a minute every day, and one doesn’t work. Which is most accurate?”

Only a matter of time.

Can I meta the question?
“Can you meta the question?”
Ooh please ooh please let me.
“<sigh>”
Taking the first derivative of the first 2 clocks’ accuracy with respect to time shows them to be equal. Therefore, since the question implies a single answer, it must be the third clock.