The answer is c. You do:
8•7•6•5
There are 8 fruits that you can choose from and every one of them can go with 7 different fruits which can go with 6 different fruits which can go with 5 different fruits.
You do that thing four times because you said that he can choose 4 fruits.
Hey -- I'll answer it for you but my vision is not that great... Could you just type the question in a reply, or DM it to me? Sorry, it's just really small on the picture, even when I tried to zoom it in.