No.702(Answers)

Black 1 is crucial.
If White 2, Black 3 kills White.

If White 2, Black 3 and 5 kill White.
White is short of liberties.

Black 1 and 3 are crucial.
The result is a Ko with the moves to Black 11.

Black 1 and 3 are wrong.
With the moves from White 2 to 12, Black dies.