Skarsnick and Gobbla have 3 damage counter on it and I activate his ability. My opponent respond by causing him one damage with flame of Tzeench. What happens ?

A : The damage from flame of Tzeench apply before I remove the three counters. Skarsnick and Gobbla dies and the effect is cancelled because I cannot pay the activation requirement.

B: The damage from flame of Tzeech apply before I remove the three counters. Skarsnick and Gobbla dies but the effect remains because it is ''stacked'' even if I cannot pay its activation cost because effects ''exist independently of their source''.

C: The damage counters are removed first because they are a condition to activate the effect. Flame of Tzeench do his point of damage but Skarsnick and Gobbla lives and the effect resume.

Thx for your answers

C) is correct.

Removing the counters is part of the cost to activate the effect. So they are gone by the time your opponent can respond with Flames.

Thanks a lot for the answer.