Karl Knechtel: I believe is correct. at b is answered by at c, and b cannot capture three to make an eye - it's a matter of white's liberties rather than black's lack of them, however.
With black cutting/trying to capture at c, as shown, white applies the same technique on the other side. Now there is a shortage of liberties situation which prevents black from cutting on this side.
White gets to connect whatever black tries, and the best black can do is get a couple of simple kos on top, but these are not life.
Of course the throw-in of does no good either. Now the a points are miai to kill, producing results from the previous diagrams.