Which of the Following Is Not True About Factors

Multiple Choice

Which of the following is not true about factors?

A) Factors whose effect on the response variable is not of interest can be set after the experiment.
B) Factors whose effect on the response variable interests us should be set at predetermined levels.
C) One way to control factors is to fix their level at one predetermined value throughout the experiment.
D) Any combination of the values of the factors is called a treatment.