Concept:Find the longest continuous carbon chain and number it from the end nearest the substituents.Explanation:The structure is CH3CH(CH3)CH(CH3)CH2CH3.The longest continuous chain contains 5 carbon atoms, so the parent alkane is pentane.There are two methyl substituents: one on carbon 2 and one on carbon 3.Therefore, the correct IUPAC name is 2,3-dimethylpentane.Answer:B. 2,3-dimethylpentane