If air resistance is present, the answer is A) the rock because it's lighter in mass. In the presence of air resistance, lighter objects, like a rock, will experience a greater proportional effect from air resistance than heavier objects, like a bowling ball. This means that the bowling ball will generally fall faster than the rock due to its greater mass and the lesser effect of air resistance relative to its weight. However, the exact outcome can depend on the size and shape of the objects as well.
If we ignore air resistance entirely, both would hit the ground at the same time in a vacuum. But since air resistance plays a role here, if the objects have similar shapes, the bowling ball will typically hit the ground before the rock. Thus, it seems there may be a potential misunderstanding in how the answers are framed based on typical physical principles.
The correct interpretation in general conditions would be that the bowling ball generally reaches the ground first in the presence of air resistance. So the most accurate answer based on standard physics is that they wouldn't hit the ground at the same time, contrary to options C and D.