In 1883, Theodor W. Engelmann conducted a classic experiment in which he illuminated a filament of photosynthetic algae with light that passed through a prism, thus exposing different segments of the algae to different wavelengths of light. He then added aerobic, nonphotosynthetic bacteria, and noted that the largest groups of bacteria were found in the areas illuminated by the red and blue light. Using what you know about photosynthesis and cellular respiration, which of the following would best explain the reason for the bacteria congregating in the regions with red and blue light?

a. The bacteria have a negative phototropic response to green light and move away from it toward the blue and red regions.
b. More bacteria congregated in the red and blue light regions because they could photosynthesize more rapidly using these wavelengths of light.
c. More bacteria congregated in the red and blue light regions because these wavelengths provide the most thermal energy.
d. More bacteria congregated in the red and blue light regions because the algae in those regions produced the most oxygen.