Imagine the following scenario: You were in class, and your professor made a guess and said

> 
> Professor: "Climate change may have led the dinosaur to extinction."
> 
> 
> 

After the class, you are about to say this sentence to your colleagues. Would you say

> 
> (A) The professor mentioned that climate change may have led the dinosaur to extinction.
> 
> 
> 

or

> 
> (B) The professor mentioned that climate change might led the dinosaur to extinction.
> 
> 
> 

or

> 
> (C) The professor mentions that climate change may have led the dinosaur to extinction.
> 
> 
> 

In fact, my question is essentially that when you want to express someone **made** a guess about the **past** event, how can we say it correctly?

By the way, I include (C) as part of possible options because it seems like when people talk about something in the past, they sometimes use the present tense rather than the past tense. Still, as a non-native speaker, I'm not really sure which is correct. I'm quite confused about it.

So, I would like to know which is the correct way to say. Or is neither of them correct by any chance? If so, how can I say it for this? I will appreciate any comment!