Answer: The correct answer is Option B.
Step-by-step explanation:
Unsaturated hydrocarbons are defined as the species in which double bond is present between carbon and carbon bonds and single bond is present between single bonds.
The general formula for these species is
where n = 1, 2, 3, 4 and so on..
Ethene is an unsaturated hydrocarbon having 2 carbon atoms and double bond is present between them.
Hence, the correct answer is Option B.