What effect will an increase in altitude have upon the available

What effect will an increase in altitude have upon the available equivalent shaft horsepower (ESHP) of a turboprop engine?

A.Lower air density and engine mass flow will cause a decrease in power.

B.Higher propeller efficiency will cause an increase in usable power (ESHP) and thrust.

C.Power will remain the same but propeller efficiency will decrease.

正确答案是A