Fill in the gap with the most appropriate option from the list provided? The principal expressed his _____when the students broke the rules _____ and he did...

Answer Details

The most appropriate option to fill the gap is "frustration / time and again". This is because the sentence suggests that the students broke the rules repeatedly ("time and again") and the principal did not know how to stop them, leading to his feeling of frustration. The other options do not fit the context of the sentence as well.