Beginner Exercise 146 / Attempts

Maybe  

tywin: looks like the best move in the circumstances. If at a, Black can jump out to b and start a semeai which it looks like he would win. I think. Anyway, if protects the corner, at a.

mgoetze: Well, there are a few things to think about when choosing a move for . First of all, what exactly happens in the semeai that ensues if White plays a directly? Secondly, what is the status of the black group in the upper right? Third, how big is a move at or near c (especially compared with a move at a)?

BTW, in the game from which I took this position, was played at a, and I suppose you can guess what I played then. ;)

HolIgor: No, you must be kidding.

ChrisSchack:The group in the upper right is alive, but anything that protects the cut at c is sente against it, requiring a response at d ... actually, I'm not sure about that last, it may depend on the semeai discussed in the upper left. If B could capture first there...