The ability to acquire food on a regular basis meant that humans a) had less control over the environment b) could give up their nonadic way of life and live in settled community's c) could use animals as pets d) could use fire to cook their food

B because since this means that humans no longer have to travel, since they can do things like farm on a regular basis.

Extra-
Choice A would be incorrect because it's the opposite of what the ability to acquire food on a regular basis. They can control and alter the environment to do things like plant. Choices C and D have nothing to do with the ability to acquire food on Ba regular basis.

4.a depression is the answer