X Company currently buys 6,000 units of a part each year from a supplier for $8.10 per part, but it is considering making the part instead. In order to make the part, X Company will have to buy equipment that will cost $150,000. The equipment will last for 6 years, at which time it will have zero disposal value. X Company estimates that it will cost $17,130 a year to make all 6,000 units. What is the approximate rate of return if X Company makes the part instead of buying it from the supplier? [Note: 0.03 means 3%, etc.] A: 0.03 OB: 0.04 OC: 0.05 OD: 0.06 E: 0.07 OF: 0.08