I put "mae'n rhaid" - I don't see a problem with Mae'n rhaid. I thought this was more correct to include the "mae'n" and a shorter more colloquial form to exclude it?
The answer with "Mae'n" should be accepted.
Thanks - i should have reported it, not just leave a comment I guess, but I accept my limitations as a learner, (I could be wrong) and I don't wish to sound like I'm moaning either.
It's fine at least if anyone else get it's wrong now they can check the asks and report it in confidence.