Question

what is the most likely reason the agricultural revolution caused a population increase?
wealthy landowners could afford to have many children.
more and better food allowed people to be healthy and well fed.
tenant farmers were able to settle down and have families.
many people moved to cities in search of jobs.

Explanation:

The Agricultural Revolution led to increased food production. With more and better food available, people had better nutrition. Good nutrition helps in reducing mortality rates (less people dying from starvation - related issues) and also supports better health which can lead to higher birth rates (as healthy parents are more likely to have healthy children who survive). The other options are not the main reason related to the core impact of the Agricultural Revolution on population. Wealthy landowners having many children (first option) is a very narrow - scale factor. Tenant farmers settling down (third option) is not the direct cause. People moving to cities (fourth option) is more related to the Industrial Revolution rather than the direct population increase from the Agricultural Revolution.

Answer:

More and better food allowed people to be healthy and well fed.