Liquids and gases transfer heat by a. air movement b. convection c. conduction d. radiation

b). convection

Explanation:

Heat or thermal energy can be transferred by conduction, convection or radiation.

when medium is rigid and molecules can not move then the most preferred way is conduction mode of heat transfer which is only possible in solids

While in liquids and gases all the molecules are not strongly connected to each other so when energy is transferred to them then molecules start moving and then transfer the energy along with it.

this mode of heat transfer is known as convection mode of heat transfer

So most favourable mode of heat transfer in liquids and gases is convection mode of heat transfer.