If it is Black's move, he can choose to make a seki by playing ...
...or, Black can choose to make a ko for the life of the White group by playing at . takes the ko first.
If Black wins the ko, he will connect at , making a crossed five. White is dead since Black can almost fill with a rabbity six.
If White wins the ko, she will make two eyes by capturing at .
Referenced byBeginnerExercise181