Answer:
D. easily
Explanation:
Let's figure out the tone of the sentence here:
"The light breeze blew ________ through the copse of trees in the woods."
The word "light" gives a sense of peacefulness and ease, something nice and airy without a negative aspect to it. From that, we can definitely eliminate A (harshly) and B (bitterly) because those words lend a kind of bad aura around the sentence.
Now look at "brightly" and "easily". Usually, since a breeze can be felt but not seen, we wouldn't describe it as "bright"; instead we usually describe a nice, light breeze as "easy".
The answer is thus D.
~ an aesthetics lover