Answer: Option (c) is the correct answer.
Explanation:
In warm air molecules have more kinetic energy. As a result, there are more number of collisions between air molecules. Hence, it rises more rapidly.
Whereas in cold air, molecules have less kinetic energy and thus they have less number of collisions between them.
Thus, in the diagram we can see that warm air begin to rise from position marked as 3 before colliding with cold air.
