Answer:
B. carbohydrate
Step-by-step explanation:
Since the only elements that are present are C, H, and O, this macromolecule must be a carbohydrate. Protein polypeptides contain nitrogen, nucleic acids contain phosphorous and nitrogen, and lipids contain phosphorous. So, the only macromolecules with just oxygen, hydrogen, and carbon are carbohydrates.
An easy way to remember:
CHO- carbs
CHON- proteins
CHOP- lipids
CHOPN- nucelotides