Can someone please check if my answers are correct?

Question

21. How do people survive living in harsh enviroments such as the desert?
a. by adapting and making changes to their enviroment
b. by moving to more hospitable areas
c. by not altering the natural landscape of their enviroments
d. none of the above
C?

23. By which of the following are modern economic systems distinguished from one another?
a. means of production
b. kinds of goods and services produced
c. amount of investment capital
d. degree of government involvment
D

Thanks
-MC

Answer 1

I think you need to look again at #21.

I agree with #22

Answer 2

Would #21 be D?
-MC

Answer 3

I would go with A.... people learn to adapt to new environments. They learn how to change their habits and in addition, the find ways to make the new environment more habitable. Think about the researchers at Antarctic

Answer 4

Alright, thank you
-MC