Choose the correct option to complete the following passage

Choose the correct option to complete the following passage.
Rivers are (1)______________of the world's most important natural resources. Many cities are on large rivers, and (2)______________every country has at least one river that (3)______________an important part in the lives of its people.
Besides transportation, rivers (4)______________food, water for crops, water to drink, and opportunities for recreation for people who live along their (5)______________. And in order to get water for crops, engineers sometimes build a dam across a river and let the water become a lake (6)______________the dam. Then people can use their water not only to (7)______________fields but also to make electricity for homes and industries.
(8)______________, the water often becomes polluted when cities on river banks grow (9) ______________size and the number of industries increases. We are learning that it is necessary to (10)______________rivers clean if we want to enjoy the benefits of the natural resources.
1.A. one
B. ones
C. among
D. those
2.A. most
B. mostly
C. almost
D. about
3.A. takes
B. makes
C. occupies
D. plays
4.A. supply
B. provide
C. distribute
D. bring
5.A. banks
B. shores
C. sides
D. beaches
6.A. behind
B. on
C. below
D. under
7.A. take
B. irrigate
C. drain
D. give
8.A. Moreover
B. Therefore
C. Thus
D. However
9.A. of
B. about
C. in
D.for
10.A.keep
B.get
C. hold
D. maintain