What forms of pollution threaten south asia today? what are their causes?

What are the causes of the water pollution that threaten South Asia today? 

overpopulation, growing cities, damming of rivers, and the need for more irrigation 

burning down of forests, building of new factories, and more cars 

the use of major rivers in religious festivals 

pollution in the Himalayan streams that drain into the region’s major rivers 
from jiskha

Yes all of them are right