Graded Go Problems for Beginners/Vol 4 Prob 18

Black to save three stones.  

From Graded Go Problems for Beginners, v. 4 problem #18. The given answer is a, and I see how that works. What I don't understand is how White can answer and . I always find Black escaping left or right or capturing White in a ladder. Can someone help me out?

dnerra I think the alternative way does not work:

The alternative way does not work.  

The cut at a may look dangerous, but it is not, as the black stones never get more than two liberties.

Do you know?  

unkx80: Ariel, I hope you know how to answer this.
ariel: unkx80, well, I worked it out....... white just hanes on the edge below black 5.......thanks for highlighting this.....:)

Because I'm a slow reader, I had to ask for help to understand ariel's response; here's one possible continuation with what I thought was a strong resistance from black (but that doesn't work, the cut at 'b' never materializes):