The correct IUPAC name of the following compound is

The correct answer is Option (4) → 4-Bromo-3-methylpent-2-ene

To name an alkene, take the longest carbon chain that contains the double bond as the parent, and number it from the end that gives the double bond the lowest locant. Substituents (here bromo and methyl) are then given their numbers and written in alphabetical order.

The compound is:

    \( \displaystyle \ce{CH3-CH=C(CH3)-CH(Br)-CH3} \)

The chain has five carbons, so the parent is pentene. Numbered from the left, the double bond starts at C2 (from the right it would start at C3), so the left end is C1. Then the methyl group is on C3 and the bromine on C4:

C1 is the left-hand \( \ce{CH3} \), C2 and C3 are the two carbons of the double bond, C4 is the carbon carrying Br, and C5 is the right-hand \( \ce{CH3} \).

So the name is 4-Bromo-3-methylpent-2-ene.