Which of these statements is a paradox?

A. The harder I work, the more I fall behind

B. You need that like another hole in the head.

C. You catch more flies with honey than vinegar.

D. Fool me once, shame on you. Fool me twice, shame on me.

a paradox is what some in American-lingo will call and oxymoron, namely, an expression that has an statement with a counterintuitive logic.

the harder I work, the more I fall behind.

what the hell? if I work harder, it should be moving ahead, but, that's not the case, I'm falling behind.

so that's a paradox, how can you work harder and fall behind? is counterintuitive, contratry to logic, therefore paradoxical.