Answer: Option (a) is the correct answer.
Step-by-step explanation:
A process in which there are two objects of different temperatures are kept together by touching each other then heat will flow from object with high temperature to low temperature is known a conduction.
Whereas a process when a fluid is heated and there occurs change material as cooler material (more dense) sinks at the bottom and hot material (less dense) rises at the top is known as convection.
On the other hand, when electromagnetic waves travel through space and energy from them heats an object without touching it is known as radiation.
Thus, we can conclude that conduction occurs when heat is transferred to an object through direct contact with particles; an example would be the heat from a stove transferring to your hand through the handle on a pot or pan.