StephaneLamy: [current position]
In this position, A18 seems equivalent to B18.
The natural follow ups B18E19A18 and A18E19B18 just interchange the order of these two moves.
JPortman: Maybe it will be a good idea to add one more possible response for the capturing side? I mean, in some problems we see a message "Correct, but what about this move?". So in this problem after the first move from the defending player (B19) the capturing player responds with B18 - the strongest response possible. But he can also respond with C19 - a slightly weaker response, but still a sente. And the defender will have two possible moves: A18 or B18 (both give him two eyes, but one is sente and another one is gote). What do you think?
Your move has been added.