:
There is no other option for Black than to start in the centre of the nakade.

:
Black has got two ko-threats only.

eliminated Black's options of cutting at , as well as attacking White's three stones in the lower left corner.

:
As already seen before, attacking White's three stones in the lower left corner does not provide Black with valid ko-threats.

:
In the problem, White would connect the ko, instead.

:
White has got two eyes, and is alive.