A punctuation question with different marks at one blank tests how parts of a sentence join. First, compare the marks’ jobs, because a period and a semicolon both separate full sentences. Then split at the blank and ask, can each side stand alone? Check who or what each side is about and what they do or are. Look for words that make either side depend on another part. A colon needs a full sentence before an explanation; a comma can attach a part that can't stand alone.
Hints
- Hint 1
Look at the word that opens the sentence, and think about what it means.
- Hint 2
Try reading each side of the blank as its own sentence. Does the opening word let the first side stand alone, or does it make you wait for more?
Step-by-step
Test the sentence, then compare the marks
Step 1Test the part after the blank
Read they play a crucial role in controlling insect populations as its own sentence. Who is it about, and what do they do? They refers to bats, and play tells us what they do, so this part can stand alone. To choose the punctuation, we also need to test the part before the blank.
- Step 2
Test the opening part
Can the words before the blank stand alone? Although means even though, so it makes us wait for what happens despite the fact about bats. The opening part says what bats are associated with, but it isn't a full sentence because although makes it depend on the main point that follows.
- Step 3
Attach it to the main point
A period would leave the opening part as a fragment, a group of words that can't stand alone. A semicolon needs full sentences on both sides, and a colon needs a full sentence before it, so neither can follow the Although part. A comma attaches the opening part to the full sentence without breaking them apart. Choice B.