What situation primarily involves heat transfer by convection?

Explanation:

In the process of convection, first the molecules of substance gets heat and becomes heated. As the molecules heated, their density decreases and hence they rises up. And the molecules which are cooler, they fall and comes in contact of higher temperature and then they rises up. the process repeats itself until the entire liquid heated uniformly.

Heating of a fluid bulk from the bottom.

Explanation:

Whenever a fluid bulk is heated form the lower layers then due to the variation of the density of the fluid at different temperature we observe the movement of molecules leading to convection.

c because the news are a source of information of things that happen on the daily and shows evidence about that particular topic

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.