Each of these questions has an assertion (A) and a reason (R).
Assertion (A) : Gandhiji withdrew the Non-Cooperatio India for some time.
Reason (R): Gandhiji believed in non-violence but the protestations by people against the British rule at Chauri-Chaura turned violent. This event disappointed Gandhiji.
Gandhiji indeed withdrew from the Non-Cooperation movement for some time. This mainly happened because the non-violent means were being compromised by certain groups, and there were incidents of violence. Hence, both A and R are true in this case, and R is the correct explanation of A.