可导致老年性痴呆的生活习惯包括（）。

A.长期饮酒 

B.吸烟 

C.经常服用镇痛药 

D.过量饮食 

E.以上都是

Marginal revenue product is best defined as the:（）

A. additional output that results from employing one more unit of a productive input.

B. gain in total revenue from selling one more unit of output.

C. addition to total revenue from selling the additional output from using one more unit of an input.