商务用餐的形式包括：（）

A.自助餐

B.便餐

C.自助餐酒会

D.商务宴会

The law of diminishing returns states that for a given production process, as more and more of a resource (such as labor) are added, holding the quantities of other resources fixed:（）

A. cost declines at an increasing rate.

B. cost declines at a decreasing rate.

C. output increases at a decreasing rate.