For number 40, we must determine if there is a punctuation change necessary, and if so, which change is needed. We can immediately see that no change is not correct because a colon does not fit here at all, colons are used to provide emphasis or an explanation for something or to introduce a list. Neither of these things are happening, so choice A cannot be correct. Looking at choice B, a semicolon does look like it can fit here because a semicolon joins together two independent clauses (an independent clause is basically just a sentence or a part of a sentence that could stand alone as a full sentence). The two parts of the sentence on either side of the semicolon are independent clauses, so a semicolon would be correct. This eliminates choice D because a comma cannot separate two independent clauses. In choice C, a “but” is not necessary because the second part of the sentence is not contrasting the first part of the sentence, so choice B would be correct.