A biologist is interested in determining which combination of factors yields the fastest growth for culinary mushrooms. He believes that the rate of growth will be affected by the number of hours of light per day, and the humidity. He decides to take samples from areas where the light was either 0, 10, or 20 hours per day, and the humidity was either "high" or "low". For each sample he records the growth of the mushrooms. This study has: (3 pts) a. one factor and five treatments. b. two factors and five treatments. C. one factor and six treatments. d. two factors and six treatments