Why can gases and liquids both transmit heat by convection

Heat transfer by convection method is used when thermal energy is transferred by the medium molecules along with the transfer of molecules itself.

When temperature of the liquid and gas is changed then due to change in temperature we will have less density of gas or liquid at the part where temperature is more.

Due to this we can say that less density molecules will move upwards and since they are weakly bonded with each other so the molecules will easily travel.

So here this type of heat transfer is possible only where the molecules are weakly bonded with each other so it is possible only in liquid and gas

so convection mode of heat transfer is not possible in solids but it is possible in liquid and gas.

i think the answer is a and b

i wish you luck