Final answer:
The compound with the molecular structure given is correctly named 3-Methylhexanal because it has a six-carbon chain with a methyl group on the third carbon and an aldehyde group on the first carbon.
Step-by-step explanation:
The molecular formula provided by the student is for an aldehyde with a total of six carbons and a methyl group attached to the third carbon from the aldehyde end. When naming alkanes and their derivatives like aldehydes, the longest carbon chain containing the aldehyde group is identified first, and then it is numbered from the end nearest to the aldehyde group. In this case, the longest chain has six carbons, and the numbering should start from the aldehyde end to give the substituents the lowest possible numbers. As the methyl group is on the third carbon, the correct naming of the compound is 3-Methylhexanal.