Here's an alternative way to catch this error: rewrite each part by substituting the pronoun with the noun it is meant to stand for, and see if the substitution still makes sense.
This substitution test confirms part (c) as the faulty segment, so option C is correct.
Let's summarize:
This technique is quick and works well whenever a sentence has more than one part using pronouns for the same person or thing.
Identify the part of the sentence that contains an error:
"Neither the manager nor the employees ___ willing to accept the new policy."