Hydrocarbon derivatives are compounds in which at least one hydrogen in a hydrocarbon is replaced by another element or group.

• A. Alkanes
• B. Hydrocarbon derivatives
• C. Alkenes
• D. Aromatics

Answer: (B)

The main idea is about compounds formed from hydrocarbons by replacing at least one hydrogen with another element or group. That substitution is what makes something a hydrocarbon derivative—the molecule is built from a hydrocarbon backbone plus a new attachment.

Alkanes, alkene derivatives? They are hydrocarbons themselves with specific bonding patterns: alkanes are saturated with only single bonds, alkenes have at least one carbon–carbon double bond, and aromatics feature an aromatic ring. None of those labels by themselves describe substitution of hydrogen with a different group; they describe the fundamental structure of the hydrocarbon, not the modified form.

Hydrocarbon derivatives, by contrast, are defined by that substitution, leading to a wide range of functional groups and classes (like halides, alcohols, esters, etc.). That’s why this term matches the given description best.