Congress cannot
a. impeach judges
b. monitor the executive branch
c. control interstate commerce
d. favor one state over another

D.

Individual members of Congress certainly are, but the structure of the legislative branch is such that it's not really possible for it to favor one state over another. Since members of congress are elected by their congressional districts, and individual senators are elected by the citizens of their state, it's natural that these members would favor their own constituencies over others
Hope this helped! :)

Interpreting the results of his experiment : )