You are studying a bacterium found in the normal intestinal flora of humans and most other mammals, and are doing an experiment to determine the optimum growth rate of this bacteria. You have inoculated five nutrient broths, and are incubating one broth at each of the following temperatures: 5oC, 25oC, 38oC, 42oC, and 55oC. At which temperature would you predict to see the optimum growth rate?