Interpret the structure

The compound corresponds to the carbon skeleton:

$\mathrm{CH_3-CH=C(CH_3)-CH(Br)-CH_3}$

We now assign the correct IUPAC name.

Choose the longest chain containing the double bond

The longest continuous chain containing the double bond has 5 carbons.

So the parent hydrocarbon is pentene.

Number the chain to give the double bond the lowest locant

Numbering from the left:

$\mathrm{CH_3-CH=C(CH_3)-CH(Br)-CH_3}$

gives:

• double bond between C-2 and C-3
• methyl substituent at C-3
• bromo substituent at C-4

Hence the parent is:

$\mathrm{pent\text{-}2\text{-}ene}$

If we number from the right, the double bond would get locant 3, which is not preferred.

Identify substituents

• Bromo at C-4
• Methyl at C-3

Write the name in alphabetical order of substituents

Alphabetically, bromo comes before methyl.

Therefore the IUPAC name is:

$\boxed{\text{4-Bromo-3-methylpent-2-ene}}$

Check options

• A: 4–Bromo-3-methylpent-2-ene ✅ Correct
• B: Incorrect parent chain / numbering
• C: Incorrect naming; not based on the longest proper parent chain
• D: Gives double bond locant 3 instead of 2, so incorrect

Comparison with stored correct answer

Stored correct answer: A

Derived answer: A

They match.