Which country started trench warfare and why?

Trenches were common throughout the Western Front.

Trench warfare in World War I was employed primarily on the Western Front, an area of northern France and Belgium that saw combat between German troops and Allied forces from France, Great Britain and, later, the United States.

Explanation:

b: the establishment clause  

b: socialism  

question 10: the answer is c, to their constituents address a problem.

question 11: i think it would be domestic bills, which deal with american issues only and public bills, which affect the whole nation.