Answer: Option (C) is the correct answer.
Explanation:
When a fluid is heated then then hot liquid (less dense) rises and cool liquid (more dense) sinks at the bottom and this process is known as convection.
For example, when cocoa mix is poured into milk and heated in an oven then molecules of milk and cocoa inter change their position due to heating and cocoa mixes into the milk.
And steam (less dense) rises at the top and cool cocoa (more dense) sinks at the bottom.
Thus, we can conclude that rising steam from the cup of cocoa is a part of this scenario in which convection can be best observed.
