You Work for an Agricultural Supply Company That Is Investigating

You work for an agricultural supply company that is investigating a new fertilizer for soybeans. You have been asked to design an experiment to compare the effectiveness of three different application amounts of the fertilizer to find the optimal amount. Each field of soybeans will be fertilized with one of the application amounts (to be determined randomly) . You think there may be large differences among different farms because of soil quality. Because of these differences, you should use a

A) completely randomized design.
B) categorical variable.
C) block design.
D) matched pairs design.
E) multistage sample.