4. In an experiment, Dr. Bay presents participants with category members such as dog, Lassie, German Shepherd, etc., and measures the time it takes participants to determine whether or not the word is a member of the category animal. In this study, what is the dependent variable?

a. The type of word presented

b. The category level of the word presented

c. Whether or not the participants answer the question correctly

d. The time it takes the participants to answer the question