Which sentence contains an error in subject-verb agreement? a. each volunteer and staff member need to arrive at the scheduled time. b. elke or carina is going to be the new dance squad captain. c. july and august are the warmest months of the year. d. some of her friends and family members are coming over for dinner.

The correct answer is A.

A subject - verb agreement means that the subject and the verb of the sentence must be in agreement in number.

With indefinite pronouns ( each, everybody, nobody etc.),  the rule is that they are always followed by a verb in singular.

Example: Everyone is wearing black.

Each volunteer and staff member needs to arrive at a scheduled time.

Each is singular because it refers to the subject being singular: each volunteer and each staff member.

i've read it so how can i ?