Consider an experiment where we're trying to determine how much water is needed to grow tomatoes. We have 16 pots with one tomato plant in each. We decide to try four different amounts of water (2 oz., 4, 6, 8). We also used 2 different types of soil (A, or B). At the end of the study, the yield of tomatoes will be measured. Given no other information, what type of design is this?

a. Completely Randomized Design

b. Completely Randomized Block Design

c. Factorial Design

d. Split Plot Design