50.
Your Answer is
Correct Answer is F
Explanation
According to the meaning of the sentence "this ban has brought about student marches and sit-in demonstrations", so the and connection is used here.
Item G: The mistake is that there is no conjunction to connect two sentences.
Item H: The mistake is in the wrong meaning, it does not mean "the ban is a sit-in demonstration".
Item J: The error is that there is no comparison object here, so there is no need for comparison.