I think the correct answer would be the third option. The correct name for the hydrocarbon described above would be 2-heptyne. It has a chemical formula written as CH3 - CH2 - CH2 - CH2 - C ≡ C - CH3. Counting the number of carbons, we have 7 carbon atoms so we use the prefix hepta-. Since it has a triple bond then it is an alkyne. So, it would be named as heptyne. The triple bond is located on the second carbon atom so we write 2 before the name to indicate the location of the triple bond. The name of the compound would be 2-heptyne.
The longest possible carbon chain should include the carbons of triple bonds.
The naming of alkyne by adding the suffix -yne.
The numbering is done in such a way that first carbon of triple bond gets the lowest number.
The carbon atoms of the triple bond get the preference over the other substituents present in the parent chain.
If two or more similar alkyl groups are present in a compound, the words di-, tri-, tetra- and so on are used to specify the number of times of the alkyl groups in the chain.
According to the given information, the name of the hydrocarbon is, 4-methyl-2-hexyne.