SPM 2014 Sebenar Objective(Chemistry). Can anyone explain how to get this answer?

[Vincent]

27.C

[D.B]

Question

27 Which compound is an unsaturated hydrocarbon?
Sebatian manakah adalah hidrokarbon tak tepu?
A CH_3CHCH_3CH_3
B CH_3CH_2CH_2CH_3
C CH_2CHCH_2CH_2CH_3
D CH_3CH_2CH_2CH_2CH_3

Answer

Hi Vincent,
Unsaturated hydrocarbon means that there is at least one carbon-carbon double bond or triple bond in the hydrocarbon chain. For this question, we will draw out the displayed formula of each hydrocarbon chain for clarity.

As you can see, there exists a carbon-carbon double bond in option C. So C is our unsaturated hydrocarbon.

[Vincent]

@D.B Thank you for taking the time to explain this, it helps me a lot