This is a very simple problem intended to teach beginners an important thing about ko.
(;C[Earlier in the game, black was the victim of the crane's nest tesuji. Now he wants to use the prospect of rescuing the five stones as a ko threat. Where should he play: A or B?FORCE]LB[kg:A]LB[ki:B]AW[ih]AW[jh]AW[lh]AW[mh]AW[ii]AW[mi]AW[ij]AW[mj]AW[jk]AW[kk]AW[lk]AB[kh]AB[ji]AB[li]AB[jj]AB[kj]AB[lj]
(;B[ki];W[kg]C[White captures 7 stones and you have lost everything locally.])
(;B[kg];W[ki]C[White captures only 5 stones, and you have two stones left in the area. Maybe they will come in handy later in the game.RIGHT]))