Explanation:

Convection is the transfer of heat by the mass movement of a fluid (such as water and air) in
the vertical direction (up and down). Convection occurs naturally in the atmosphere and
convection is one process by which clouds can form. Convection is usually the dominant
form of heat transfer in liquids and gases. Hence, option (b) is the correct answer.
The transfer of heat or matter by the flow of a fluid, especially horizontally in the
atmosphere or the sea is called advection.
Conduction is the transfer of heat from molecule to molecule within a substance. Molecules
must be in direct contact with each other.