The IUPAC name of the following compound is
1-Ethyl-2,2-dimethylcyclohexane
2,2-Dimethyl-1-ethylcyclohexane
1,1-Dimethyl-2-ethylcyclohexane
2-Ethyl-1,1-dimethylcyclohexane
Numbering will be done on the basis of lowest locant rule.
Alphabetically ethyl comes before the methyl group.
So, IUPAC name of the compound is 2-Ethyl-1,1-dimethyl cyclohexane
Therefore, option (4) is correct.