[Grammar] Question

[Mauricio]

In this question,

What would it be the right answer ?

- Do you swim every day ?
- I used to swim every day, but now I just swim six days a week.

The reporter asked M.P --------------------every day

a) did he swim
b) if he is swimming
c) if he swam
d) is he swimming

Thanks,
Mauricio

 

[mmasny]

And what is your opinion?

 

[Mauricio]

In my opinion, the right answer would be letter A , despite I do not know this structure....

So ?

 

[billmcd]

c) "if he swam"- Reported question ruleast tense.