Hi,

Which is the best answer?

I've corrected the English in the sentences that describe the pictures.

(a) The picure shows B is already on the ladder plucking the mangos while A is holding the ladder under the tree.  

       A: (i) Why are you plucking them?

           (ii) Pluck them carefully.

A could say either of these things.

      B: These mangoes are ripe and juicy. 

This is not a direct answer to A(i), but it is acceptable. More direct would be 'Because they are ripe and juicy'.  

A(ii) is not a question, and thus requires no answer. However, B could say this, to continue the conversation.   

(b) The picture shows 2 boys are playing on the slide. A is going/has gone down the slide while B is getting ready to slide.

      A: Wow! This is fun.

      B: (i) It's my turn next.

          (ii) I'm happy.

A is not asking a question, and thus requires no answer. B could say either of these things, to continue the conversation. B(i) might fit what is shown in the picture better.

Best wishes, Clive