Siméon:
After checking the given solution, it is wrong as w would not connect but create a ko. So sacrifing the 2 stones seems mandatory (except I missed something obvious)

Siméon:
B 2-2, w 3-2 (atari), b 1-2 is tagged incorrect but although maybe not the best way, black is alive anyway :)

babao:
Perhaps it would be better for the opponent to answer with T2 after R3 to show the player the double ko. That way it becomes clear that throwing away the R4 stones is a mistake. Vyacheslav's sequence is also alive but is a worse result.

Vyacheslav:
B18-B17-A18-C17-C18 looks alive

Vyacheslav:
B2-B3-A2-C3-C2 looks alive

Husrev:
This is also alive.