A chemical plant with a capacity of 6,000 kg/day requires a fixed capital investment of $10 million with a working capital of 25% of the total investment. In operation, it requires an annual variable production cost of $2,000,000 and a fixed cost of $700,000. If the resulting product sells for $3.45/kg, how long is the payback period of the chemical plant if it is assumed that the interest rate = 10% and the plant operates 330 days/year?
A. 4.1 years B. 5.1 years C. 3.1 years D. 7.1 years