Hint: Look for properties of homologous series.

Explanation:

A series of compounds that have the same general formula, the same method of preparation, and chemical properties, the same functional group is called a homologous series. The adjacent member differs in CH₂ unit.
The members do not have the same molecular weight.
Hence, Option B is correct.
The homologous series of alkane, alkene, and alkyne is shown as in below diagram;