Air is a bad conductor of heat because:

A

it's molecules are in continuous contact with each other.

B

it's molecules are not in continuous contact with each other

C

it's molecules absorb all the heat

D

it's molecules are moving randomly due to Brownian motion

Air is a bad conductor of heat because it's molecules are not in continuous contact with each other.
Air molecules are too far to disperse heat energy to one another efficiently. Heat is conducted by molecules and atoms that are very closely bonded together and vibrating at high frequency.