Is 가장 means "the most"?
What about 제일?
제일 also correct
For helping your learning, Other two sentences in this quiz are perfectly wrong. There is no sentences like that in Korean.
Why does Duolingo often make these wrong sentences? It makes learners confused.
아이들이 가장 심심한 영화를 봅니다?
Nope, this means "bored" nor "boring"
Not just this item: For the a, b, c choices, one cannot see the TOPS of the Hangeul letters given.
i could not edit my post in this app so i deleted it.
Most likely computer browser settings if on web. And not present in mobile app. Either way report specifics online.