求助OG 98谢谢

Hotco oil burners, designed to be used in asphalt plants, are so efficient that Hotco will sell one to the Clifton Asphalt plant for no payment other than the cost savings between the total amount the asphalt plant actually paid for oil useing its former burner during the last two years and the total amount it will pay for oil using the Hotco burner during the next two years. On installation, the plant will make an estimated payment, which will be adjusted after 2 years to equal the actual cost savings.

Which of the following if it occured , would constitute a disadvantage for Hotco of the plan descrubed above?

a. Another manufactuer's introduction to the market of a similar efficient burner

b. The Clifton Asphalt plant's need for more than one burner

c. Very poor efficiency in the Clifton Asphalt plant's old new burner

d. A decrease in the demand for asphalt

e. A steady increase in the price of oil begining soos after the new burner is installed

答案为E， 但是既然油价上涨，旧款和新款的BURNER 耗油量都不变，那么COSTSAVING 不是增加了吗，那个卖机器的公司应该更有利啊？