Control Is Important in Experimental Research

Control is important in experimental research. Which of the following statements is true in regard to control in an experimental study?

A) Control is obtained by randomly assigning people to treatment groups.
B) Ideally, in an experimental research study, all groups are treated the same except for the treatment variable.
C) Control is sometimes obtained by matching people before assigning them to groups.
D) Control is sometimes obtained by using a control group.
E) All of these are correct.