Identify a hydrocarbon pair that is NOT the part of the homologous series.

A

$$ CH_{4}$$ and $$C_{2}H_{6}$$

B

$$C_{2}H_{6}$$ and $$C_{3}H_{9}$$

C

$$C_{2}H_{6}$$ and $$C_{3}H_{8}$$

D

$$C_{4}H_{4}$$ and $$C_{5}H_{10}$$