The series of TV program that has just finished ... very useful

The answer options for this question are: wasn't, are, were, weren't.

Answer:

The series of TV program that has just finished wasn't very useful.

Explanation:

"The series of TV program" represents the pronoun "It", which means that among the options given in the question the only one that represents the correct option is "wasn't".

As we already know, the pronouns "she", "he", "it" use the verb in the form "wasn't" and not "weren't"