Hrewsahgs: This variation is seki, so it should be pruned, I think. The attackers's strongest resistance is A19 instead of A18, allowing the defender to live with points in double ko. Not sure which one's worth more...seki, or life with points at the expense of the attacker becoming a komonster.
Ivan Detkov: A19 is bad for the attacker, right? The group is alive in the double ko. A18 makes seki and it should be marked as the correct solution and it looks like the best solution because it is seki in sente. Do you agree?
This variation is seki, so it should be pruned, I think. The attackers's strongest resistance is 
Marked A16-B18-C18-A18-B19 as correct.