Answer
D. propyl butanoate
Explanation:
The general formula of an ester is RCOOR'. Esters are named as if the alkyl chain from the alcohol is a substituent. No number is assigned to this alkyl chain. This is followed by the name of the parent chain from the carboxylic acid part of the ester with an –e remove and replaced with the ending –oate.
Therefore, the name of the given ester molecule is:
D. propyl butanoate.
