There's no proof of what {you're saying/you said/you say} - which tense is correct?

Question

What tense should I use in this case?

Let's say that John and Paul are having a conversation. John claims to know something. Paul doesn't believe him. Which of the following answers is the most appropriate for Paul to say?

A) There's no proof of what you're saying.

B) There's no proof of what you said.

C) There's no proof of what you say.

To my ear, they are all grammatically correct.

A) maybe emphasizes the fact that John has been trying to persuade Paul for some time, perhaps by giving different kinds of information.

B) makes me think that Paul is referring to just a single claim that John made.

C) probably is the most neutral.

Am I correct?

Answer 1

A) There's no proof of what you're saying.

B) There's no proof of what you said.

C) There's no proof of what you say.

All three examples are grammatical. However, as (A) is the most specific on the on-going claims, it could be the most appropriate.

In these examples, the number of claims does not affect the what-clause to use.