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:

农业革命（Agricultural Revolution）的核心是农业生产方式的改进，使得粮食产量增加。从人口增长的基本逻辑看，食物是维持生命和繁衍的基础。“Wealthy landowners could afford to have many children”只强调了富人，不能代表整体人口增长原因；“Tenant farmers were able to settle down and have families”，定居只是一个方面，没有直接关联到人口增长的关键因素（食物等生存资源）；“Many people moved to cities in search of jobs”是人口流动，和人口数量增加没有直接因果关系。而“More and better food allowed people to be healthy and well fed”，更多更好的食物能让人们健康（降低死亡率）、能养育更多后代（提高生育率），符合人口增长的根本逻辑（生存资源保障）。

Answer:

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