One of the following is not a requirement of experimental design:.
A) Multiple measures must be taken before and after exposure to the independent variable
B) The independent variables are introduced or manipulated, one at a time, by the researcher
C) There are one or more control groups that are not exposed to the independent variable.
D) Research participants are randomly assigned to experimental and control groups

Option c

Explanation:

In experimental design, there are lots of test to certify the essence of the design. When there exist an independent variable, every measure of control is applied to it to test if it measures the expectation ,so there can't be one or two control measure not applied to the independent variable, we have to test every respective attribute of the control measure, we have randomly apply different theories to see if the control measure with its independent variable meets standards that is why Option C is not a requirement

answer; i believe the correct answer is norming;