Hint: The longest carbon chain contains seven carbon atoms.
The longest carbon chain contains seven carbon atoms. Thus parent chain is heptane. Numbering of the chain is done in such a way that ethyl group gets lowest position. The compound with numbering is as follows:
The IUPAC name of the compound is 3-Ethyl-4,4-dimethylhexane. Hence option one is the correct answer.
4,4-Dimethyl-3-ethylheptane is wrong because alphabetically ethyl will come first than methyl.
5-Ethyl-4,4-dimethylheptane is wrong because lowest sum rule doesnot follow while numbering the chain.
4,4-Bis(methyl)-3-ethylheptane is wrong because bis is not used.
