Interesting puzzle!

Have a look at this interesting puzzle. Black's move seems obvious but how do you reply to White's move?

https://www.chess.com/forum/view/more-puzzles/how-is-this-puzzle-rated-2000?page=1#comment-52364952

This is where I got the puzzle from. Please do not go there until you have solved the puzzle unless you give up.

If yu have the answer, don't put it in the comments and if you do put it in white font so that the people who know the answer can highlight it to check it but you don't give the answer away.