Why Is It Important to Make Sure That Different Participant

Multiple Choice

Why is it important to make sure that different participant groups are roughly equivalent in terms of personal characteristics (e.g. ,age,gender) before any independent variable is introduced?

A) It is important to treat all research participants equally so that they feel that they are not being manipulated.
B) Research ethics forbid any experiment to take place when the participant groups are fundamentally different from each other.
C) It is important so that no major differences between the groups unduly bias the results of the experiment.
D) This is generally what happens when participants are allowed to choose their own groups.