Which of the Following Is Correct with Regard to the Use

Which of the following is correct with regard to the use of matched groups as a method of experimental control?

A) We can assure control over any irrelevant variable that might affect the results
B) We may "match out" too much or too little
C) Matching should be used instead of random assignment where possible in order to assure more precise control
D) Through matching we can usually compensate for any inadequacies in our research design