设施质量管理的核心是( )。

A．授权给雇员，让他们承担责任
B．使用全面的、管理良好的回馈系统
C．能够接受评价与评价自身
D．持续改进技术水平和管理水平

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 calorie 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．(E) As few as 20 different food crops provide the bulk of the planet’s food supply.