"On the suit."
Translation:Ar an gculaith.
Yes, in the Official Standard there are rules about it. They are listed under the eclipses and lenition units here. One rule is with certain prepositions + the definite article, an eclipsis is required, regardless of the noun gender. In which case, you don't lenite. The prepositions that do this should be listed in the eclipses unit notes), but here are few examples:
Leis an gcailín - with the girl
Ar an gcapall - on the horse
Ag an mbean - at the woman
Ón bhfear - from the man (remember that ón is ó + an)
It wasn't clear to me in the eclipsis notes if they would take precedence or not when overlapping with lenition cases. I had not consciously realized "conflicts" could happen, and this exercise here made me see it had happened in a few cases on duolingo already.
Thank you for the clarification!
Perhaps they overlooked that. There's a lot to take in with eclipses, I know. But yeah, with any of the incidences listed there in the notes of when to use the ellipsis, the eclipsis will take precedence and you will not use lenition.
preposition + an causes eclipsis for all nouns that start with b, c, f, g or p regardless of gender.