Answer:
The answer is actually : Decreases in membership at the club are affecting
Step-by-step explanation:
The decrease in members at the club are affecting the ability of the club to maintain its staff. is the original sentence, and by changing it to "Decreases in membership at the club are affecting" makes it correct.
The answer listed where the choice says Decreases in membership at the club is affecting... seems correct to grammerly, however just taking the test it is not correct