Scientists have rediscovered certain food crops, once commonly cultivated in the New World, which contain more protein per pound than do current staple food crops such as rice and wheat. Scientists claim that cultivation of these crops could greatly benefit densely populated countries that have low per-person caloric intake and inadequate source of protein. Which of the following, if true, casts the most serious doubt on the claim made above？

A. The average yield per acre of the rediscovered crops is substantially less than that of the current staple food crops.
B. Many important food crops, such as tomato, originated in the New World.
C. Wheat yields more protein per pound than does rice.
D. The rediscovered crops have more caloric per pound than do current, staple food crops.
E. As few as 20 different food crops provide the bulk of the planet"s food supply.