Could it also be they do not like the skirt?
With context, yes.
That's what i wrote and it said it was wrong. App should be better at taking these alternative answers
Got this as an audio question, and it sounded a lot like they were saying "Roh" rather than "Rok" That answer was accepted as well.
In my experience, you only use explicit plurals in Indonesian when you want to emphasise the plurality. In thise case you're talking about the general concept of skirts, so no need to pluralise.
And how do we know if it's plural or not?