Pumpkin patch: Suppose we plant pumpkins in a garden where half of the plants are shaded. Then, to test a new fertilizer, we fertilize the plants in full sun and do not fertilize the plants in the shade. In the fall the fertilized plants yield more, bigger, and prettier pumpkins. Which of the following did we fail to include in the experimental design? A. Fall season.
B. Fertilizer.
C. Pumpkin harvest.
D. Amount of sunshine.

B. Fertilizer.

Step-by-step explanation:

In this experiment, you actually failed to include the fertilizer. This is because you are only fertilizing the pumpkins in the sun and not the shade. Therefore, you really do not know if the pumpkins that grew larger and prettier did so because of the fertilizer or the sun. What you should have done was either fertilized all pumpkins, none of the pumpkins, or half of the ones in the sun and half of the ones in the shade. That way you can correctly isolate the effect of the fertilizer on the pumpkins growth.