An airplane factory manufactures airplane engines. The unit cost c(x) (the cost in dollars to make each airplane engine) depends on the number of engines made. If x engines are made, then the unit cost is given by the function c(x)=−0.9x²-306x+34,590. What is the minimum unit cost?
A) $34,590
B) $306
C) $17,295
D) $0
