
Passage: There is a TV commercial saying that black chicken grown in the green prairie eats grass when hungry, and eats grasshoppers when greedy, which seems to imply that the nutritional value of this chicken and its eggs is related to the prairie food that the chicken eats.
Question: In order to verify this conclusion, which of the following experimental methods is the most reliable?
A. A.Select an elite breed of laying hens and put them on the prairie, and then compare the nutritional content with ordinary chicken not raised on the prairie.
B. B.Assay and compare the nutritional content of prairie chicken food and non-prairie chicken food
C. C.Select laying hens of the exact same breed grade, put half on prairie and half on non-prairie, and compare their nutritional content.
D. D.Select laying hens of different breeds, feeding them on the prairie, and compare their nutritional content.
Answer: