A patent was purchased for $670,000 with a legal life of 20 years. Management estimates that the patent has an 12-year economic life. The entry to record amortization would include: Select one: a. a decrease in patent for $55,833 o b. an increase in amortization expense for $33,500 . X c. an increase in accumulated amortization for $670,000. d. an increase in research and development expense for $670,000