An agricultural station is testing the yields for six different varieties of seed corn. The station has four large fields available, which are located in four distinctly different parts of the county. The agricultural researchers consider the climatic and soil conditions in the four parts of the county as being unequal but are reasonably confident that the conditions within each field are fairly similar throughout. The researchers divide each field into six sections and then randomly assign one variety of corn seed to each section in that field.

This procedure is done for each field. At the end of the growing season, the corn will be harvested, and the yield, measured in tons per acre, will be compared. Which one of the following statements about the design is correct?

(a) This is an observational study because the researchers are watching the corn grow.

(b) This a randomized block design with fields as blocks and seed types as treatments.

(c) This is a randomized block design with seed types as blocks and fields as treatments.

(d) This is a completely randomized design because the six seed types were randomly assigned to the four fields.

(e) This is a completely randomized design with 24 treatments—6 seed types and 4 fields.