I think that the beginning of the question says "ill health"
Yes, this is true. low earnings are often correlated with bad health - it's because poor people have less access to health care, less access to healthy food and might be forced to do jobs which are stressful and demanding.
I would say D.
because you can’t count on foraging to feed 100 people, whereas agricultural growing of food is more effective when you have more people. you can plant 100 seeds, but you can’t guarantee to find 100 berries while foraging. hope this helps!
