Which of the Following Statements About Matched-Pairs Sampling Is Correct

Multiple Choice

Which of the following statements about matched-pairs sampling is correct?

A) It is a procedure that matches each unit from population A with a "twin" from population B so that any sample observation about a unit in population A automatically yields an associated observation about a unit in population B.
B) It is designed to control for extraneous factors that might influence the characteristic being measured in addition to the variable under study.
C) When testing the effectiveness of a new drug compared to a traditional one, each patient in an experimental group might be matched with a partner in a control group of the same age, weight, height, sex, occupation, medical history, lifestyle, and so on.
D) All of these.
E) None of these.