Which of the choices best completes the sentence below? unfortunately, the lawn spark plugs needed replacing

a: mower's
b: mowers
c: mowers's
d: mowers'

The correct choice would be A. mower's.

When you say mowers, that would indicate that you are talking about more than one mower because it is in plural form. When you say mowers's, that would indicate that you are referring to more than one mower. Mowers's is incorrect because you say lawn mower and not lawn mowers, unless you are talking about more than one mower. 

Eric schlosser. if i'm thinking rihtbthen it's him. and if i read the question right then yes