Jenae noticed that many of her co-workers would opt for the coffee that appeared to be most recently brewed, regardless of the flavor of the coffee offered. This leads her to believe that what she was witnessing was not really representative of everyone's true flavor preferences. She adapted her experimental study accordingly. Select one control in Janaes experimental study:

a. Jenae uses different locations in the kitchen for the coffee pots.

b. Jenae makes sure that the coffee in different pots is brewed at the same time.

c. Jenae places condiments at random places throughout the kitchen.

d. Jenae monitors the habits of the co-workers who do not drink coffee.