D. is wrong. It should be "One hero in the animation field is Mel Blanc, the voice behind many cartoon characters." because the information after Mel Blanc is not necessary to the sentence. It's just extra, so you need a comma.
4. vignettes is the answer!
Answer: The imposing height of giraffes is the secret to their ability to thrive in their often-dry environment. It helps them reach the acacia trees' tender leaves that are only at the top.
Explanation:
I hope this helps :)