Correct Answer: talks about

Solution : The correct choice is the fourth option.

The original sentence is in the future tense, indicating a future action. In this context, the use of "will talk" implies that the person will discuss films in the future. "Talks about" is the correct choice, as it maintains the present tense and indicates a habitual or ongoing action. It reflects the idea that he consistently talks about films, making it a suitable replacement for the original sentence.

Therefore, the correct sentence is: He talks about nothing but films.