Arsenic contamination of groundwater in the u. s., china, and many other countries comes from: select one:
a. nuclear power plants.
b. municipal wastewater.
c. agricultural runoff.
d. weathering of bedrock and sediments
e. septic systems.

I'm hella smart but i dont know that

Ibelieve it would be religious 

Answerseasonal dry and wet winds this answer is right outta of the book

1. why do astronomers think that there may be other advanced civilizations?
because  it was discovered that there are other planets like earth out there, able to  accommodate life forms.
2. what technologies are astronomers using to look for life on other planets? why?  
they  have used radio telescopes, but now they use laser telescopes   to track laser communications.