A Researcher Is Interested in Whether a New Reading Program

A researcher is interested in whether a new reading program for 5th graders will lead to better performance than a traditional program. She is also concerned that the program effects might vary or be confounded with prior reading achievement. Hence, she includes prior reading achievement in her study as a variable. The control technique she used in this study was:

A) Matching
B) Random assignment
C) Holding the extraneous variable constant
D) Building the extraneous variable into the design