Answer:
The sentence that has a correct subject/verb agreement is:
B. Neither the televisions nor the radios work.
Step-by-step explanation:
When a compound subject is joined by "nor", we must pay attention to the element that is closer to the verb. If that element is singular, then the verb should be singular. If the element is plural, the verb must also be plural.
Having that in mind, we can see why letters A, C, and D are incorrect. In letter A, the element that is closer to the verb is "cellphones", plural, but the verb is "works", singular. In letter C, the element closer to the verb is "watch", singular, but the verb "work" is plural. Finally, in letter D, the element closer to the verb is "trucks", plural, but the verb "works" is singular.
It is letter B that has a correct subject/verb agreement. The element that is closer to the verb is "radios", plural, and the verb "work" is also plural.