Identify the required groups

We need a hydrocarbon with 7 carbon atoms that contains:

• a neopentyl group: $\ce{(CH3)3C-CH2-}$
• a vinyl group: $\ce{CH2=CH-}$

Combine the two groups

If a molecule contains both neopentyl and vinyl groups, its structure can be written as: $\ce{CH2=CH-CH2-C(CH3)3}$

Count carbons:

• vinyl part: $2$ carbons
• $\ce{CH2}$ linker: $1$ carbon
• quaternary carbon: $1$ carbon
• three methyl groups: $3$ carbons

Total $= 2+1+1+3 = 7$ carbons.

Find the IUPAC name of this structure

Structure: $\ce{CH2=CH-CH2-C(CH3)3}$

Choose the longest chain containing the double bond: $\ce{CH2=CH-CH2-C-CH3}$

This gives a pentene chain. Number from the double-bond end to give the alkene lowest locant:

• double bond at carbon $1$
• two methyl substituents at carbon $4$

Therefore, the name is: $\boxed{4,4\text{-dimethyl-1-pentene}}$

Match with the options

Among the given options, option C: 4, 4-dimethylpentene represents this structure (the position of double bond is omitted in the option, but it corresponds to the required neopentyl + vinyl arrangement).

Check other options briefly

• A: 2,2-dimethyl-4-pentene corresponds to a different skeleton; it does not contain the neopentyl fragment.
• B: Isopropyl-2-butene has only $6$ carbons, not $7$.
• D: 2,2-dimethyl-3-pentene also does not give the neopentyl + vinyl combination.

Final answer

The required hydrocarbon is: $\boxed{\text{C}}$

Comparison with stored answer

Stored correct answer: C

My derived answer also is C, so they agree.