They are all correct, natural and perfectly comprehensible.
To me, 1 is the most natural. It is impossible to give reasons for one`s choice of the most natural. The judgment comes from the sum total of a lifetime spent hearing and speaking your native tongue. And therefore it depends on where you spent your life. I think that 3 is a close second to 1 and 2 is slightly less natural, but I suspect that native speakers from elsewhere may well have other opinions.
- For Teachers