The correct answer is B. 4-methylhex-1-ene.
The longest carbon chain in the molecule has 6 carbons, so the parent alkene is hex-1-ene. There is a methyl group attached to carbon number 4, so we name it 4-methylhex-1-ene.
Here is a step-by-step guide to naming alkenes using the IUPAC system:
1. Identify the longest carbon chain that contains the double bond. This is the parent alkene.
2. Number the carbons in the parent chain, starting from the end that is closest to the double bond.
3. Identify any alkyl groups attached to the parent chain. These are called substituents.
4. Name the substituents and indicate their position on the parent chain using the appropriate locants.
5. Add the prefix "ene" to the name of the parent alkene to indicate that it is an alkene.
Example:
The following alkene is named 3-methylhex-2-ene:
CH3-CH(CH3)-CH=CH-CH2-CH3
* The longest carbon chain that contains the double bond has 6 carbons, so the parent alkene is hex-2-ene.
* There is a methyl group attached to carbon number 3, so we name it 3-methylhex-2-ene.