What can't congressmen do?
27th Amendment

Prohibits any law that increases or decreases the salary of members of Congress.

Explanation:

The Twenty-seventh Amendment (Amendment XXVII) to the United States Constitution prohibits any law that increases or decreases the salary of members of Congress from taking effect until the start of the next set of terms of office for representatives.

answer; disconfirm the catharsis theory;

answer; geography and region;