I would've thought 'cén uair'
That's the answer i see as correct. Both cén uair and cá huair should be correct.
What are the literal translations of both of those?
My impression is:
Cén uair = which hour
Cá huair = what hour
When it asks me to pick all correct responses in multiple choice, it requires "cén uair" and "cá huair" in order to be correct.