Concept:The compound is an alkyl bromide whose common name is derived from the alkyl group attached to bromine.Explanation:The structure is (CH3)2CHCH2Br.It contains a four-carbon alkyl group arranged as a branched chain.This branched alkyl group is called the isobutyl group.When bromine is attached to the isobutyl group, the common name is isobutyl bromide.Its IUPAC name is 1-bromo-2-methylpropane, with formula C4H9Br.Answer:Isobutyl bromide (Option A).