You can use which one/whichever one/the one you want.

[navi tasan]

1) You can choose which one you want.

Is that sentence correct?

I think it is correct, but I use 'whicever one' or 'the one'.

 

[5jj]

All three are possible (if you correct the spelling of whichever).
Whichever and which (without one) are also OK.

 

[emsr2d2]

I think it is correct, but can I use 'whichever one' or 'the one'?