A mechanical testing machine with an initial cost of $11.000 closely follows the cost pattern shown below 3,950 4.200 4,700 5,400 6,300 Year Operationg 3,700 Cost, $ Salvage Value, 8,500 7,200 7,600 6,400 5.000 3,600 2,200 800 Assume that replacement equipment will follow the same cost pattem (a) What is the economic service life of the machine if MARR is 0%? OA. 3 years OB. 2 years OC. 4 years OD. 5 years (b) At an interest rate of 8%, what would be the annual cost of the machine if it is kept for three years? O A. $-6,614 OB. $-6,234 OC. $-6,424 OD. $-6,045