One gate is not enough

The circuit needs to recognise one exact combination: A=1, B=0.

Could AND do it?

No. AND only outputs 1 when both inputs are 1. In every other case, it outputs 0.

Could OR do it?

Almost. OR outputs 1 for A=1, B=0. But it also outputs 1 for A=0, B=1, when B is bigger.

Neither gate can recognise the right combination alone.