The U.S. Postal Service used to be a government corporation, but in the early 1970s it was transformed into a private corporation.

In experimental research, extraneous variables are always

A) between-group variables. B) within-group variables. C) organismic variables. D) response variables.

Individual states have primarily concerned themselves with combating environmental challenges ______.

a. within their own borders b. that impact the entire planet c. that they have particular expertise with d. when they are harming neighboring countries