"Answer!"

Translation: जवाब दो!

[Sam362597]

I think the exclamation mark makes it clear that you need to use the imperative.

[Ellen147987]

Why two words suddenly? This came unexplained duolingo style or had we learned the verb to answer?

[LobsangC]

It means 'give the answer', the first word is actually a noun and the second word is the imperative form of 'give'.