Doctors Chase and Sanborn are conducting an experiment on the effects of caffeine on memory. Participants are randomly assigned to a caffeine or a no-caffeine group; their recall of items on a word list is later assessed. Which pair below correctly names and identifies the variables in this experiment?

A. Word recall—control variable; caffeine—experimental variable
B. Word recall—independent variable; caffeine—dependent variable
C. Word recall—dependent variable; caffeine—independent variable
D. Word recall—experimental variable; caffeine—control variable