Mrs. Woods and Mrs. Bryan are avid vegetable gardeners. They use different fertilizers, and each claims that hers is the best fertilizer to use when growing tomatoes. Both agree to do a study using the weight of their tomatoes as the response variable.

They had each planted the same varieties of tomatoes on the same day and fertilized the plants on the same schedule throughout the growing season. At harvest time, they each randomly select 15 tomatoes from their respective gardens and weigh them. After performing a two-sample t test on the difference in mean weights of tomatoes, they get t = 5.24 and P =

0.0008. Can the gardener with the larger mean claim that her fertilizer caused her tomatoes to be heavier?

(a) Yes, because a different fertilizer was used on each garden.

(b) Yes, because random samples were taken from each garden.

(c) Yes, because the P-value is so small.

(d) No, because the soil conditions in the two gardens is a potential confounding variable.

(e) No, because there was no replication.