Final answer:
The correct sentence is 'Neither of the brothers has seen his children in ten years'. The subject 'neither of the brothers' is singular so we should use 'has' not 'have'. We should also use 'his' instead of 'their' so that it's clear that we are referring to each brother individually.
Step-by-step explanation:
The subject of the sentence is 'Neither of the brothers'. The verb should agree with the subject in a sentence, which makes 'neither of the brothers' singular. Thus, we should use 'has' instead of 'have'. Consequently, the statement should read like this: 'Neither of the brothers has seen his children in ten years'.
Furthermore, it's preferable to use 'his' instead of 'their' in order to make it clear that each brother individually has not seen his children. '
So, the correct sentence is 'c. Neither of the brothers has seen his children in ten years'.
Learn more about Subject-Verb Agreement