The exciting final act was able to redeem an otherwise terrible play.

1. to buy back or pay off;
2. to exchange for something else;
3. to make up for or make more acceptable;
4. to release from blame or debt.

Which definition in the entry best clarifies the precise meaning of the word redeem in this sentence?

a. definition 1 .
b. definition 2
c. definition 3
d. definition 4