Carboxylic acids react with alcohols to make esters. A small amount of concentrated sulfuric acid is used as a catalyst. Consider the following ester: What is the name of the alcohol that was used to form this ester?

Answer:

14) H

The part of the ester molecule highlighted in the green square represents the alcohol used to make the ester. It has 3 carbon atoms and the oxygen atom (part of the hydroxyl group of alcohol) is on the second carbon.
So the answer would be propan-2-ol.