Biology

The correct answer is: C.unlimited resources.

Explanation:

Exponential growth in a population occurs when there are no significant limiting factors, such as resource shortages, and the population can grow rapidly. Unlimited resources (like abundant food, space, and shelter) allow the population to continue growing at a constant rate, with each new generation reproducing at an accelerating pace. This results in exponential growth, typically represented by a J-shaped curve.

Here's why the other options are not correct:

A.People lifting heavy stuff: This has no direct effect on population growth. It may affect work output or labor, but it doesn't influence the rate at which the population increases.