BeginnerExercise237/Solution

path 1 - optimal  

Black gets the 3 white stones in a snapback

path 1 - why not protect?  

If would protect against the snapback, Black would cut white in two killing more white stones.

path 1 - why go for all?  

Because White can just capture the cutting stones then.

path 2  

prevents a snapback

path 3  

prevents a snapback

path 4  

A variation of path 2

billyswong: However, in path 2 and 3, white results with loss of more than the original 3 stones with no gain. But the snapback in path 1 can be used as a ko threat later on.