For a moment I was struck in between two statements. its a trap if you don't read the question again.

why do I get it correct in BR only.

I got tripped at the same line. but in the BR I choose B.

Correct Quantifiers help here. Many->Some->At least one. Most->Some. If I don't think about quantifiers I would trip.

This is the main crux: If the sufficient condition is failed, it yields no information about the necessary condition (Bird).

Wow! how long you have been practicing!

Any tips to improve our score!