Convection:

• When a fluid, such as air or a liquid is heated and then travels away from the source, it carries the thermal energy along, this type of heat transfer is called convection.
• Convection is the process of heat transfer and this happens when a gas or liquid is heated, this heated liquid tends to heat the other liquid or gas which is in contact with it, this transferred heat is in the form of thermal energy and this whole process is known as convection.

Hence, the correct option is (B).