one factory manager bought a rare machine for $10 million. It is estimated that the sales value of the machine at the end of the first year will be $3 million and the machine will be worth $500,000 due to the demand by the antique dealers. The maintenance cost is expected to be $300,000 in the first 3 years and double each year thereafter. In this way, the maintenance cost of the 4th year is $600,000, the maintenance cost of the 5th year is $1,200,000, etc. Calculate the economic life of this machine based on a 15% MCVO.

A) 7 B) 3 C)12 D) 6 E) 9