You may have observed plants rotate towards a light source, thereby increasing the plant's ability to intercept light energy and increase photosynthesis. You, however, are given the task of preventing grass seedlings from rotating toward the light. Using your knowledge of phototropism, which of the following experimental procedures would you use to complete your task?
a. Cover the growing tip of the grass seedling with black paper.
b. Supply the seedlings with very dim light (red light does not induce a bend).
c. Cover the portion of the seedling below the tip with a black shield.
d. Supply the seedling with nutrient-rich fertilizer solution.