Question

a scientist wants to determine which fertilizer is more effective—fertilizer x or fertilizer y. the best way for her to proceed would be to design an experiment with

a. three groups of plants—a group fertilized by x, a group fertilized by both x and y, and a control group with no fertilizer.
b. three groups of plants—a group fertilized by x, a group fertilized by y, and a control group with no fertilizer.
c. two groups of plants—a group fertilized by y and a control group with no fertilizer.
d. two groups of plants—a group fertilized by x and a control group with no fertilizer.

Explanation:

To compare the effectiveness of Fertilizer X and Fertilizer Y, we need groups with each fertilizer and a control group for baseline comparison. Having a group with both fertilizers confuses the results as we can't tell which one is more effective. Just having one - fertilizer groups won't allow for a comparison between X and Y.

Answer:

B. three groups of plants—a group fertilized by X, a group fertilized by Y, and a control group with no fertilizer.