Robert decided to use blocking to deal with an extraneous factor in his
experiment. What will blocking do to the subjects in his experiment?

A. Divide them into groups based on whether he likes them
B. Divide them into groups based on an alphabetized list
C. Divide them into groups based on similarities

D. Divide them into groups randomly

D. Divide them into groups randomly

Step-by-step explanation:

The point of blocking is to ensure randomization. To have an unbiased experiment, you need randomization, because if your groups are unbalanced (say, we have one group all females and one group all males) you can't attribute your findings to the variable under study, because of the possibility that it could be due to other noise factors.