A patent was purchased for $670,000 with a legal life of 20 years. Management estimates that the patent has an 8-year economic life. The entry to record amortization would include:
a) an increase in amortization expense for $33,500.
b) an increase in research and development expense for $670,000.
c) a decrease in patent for $83,750.
d) an increase in accumulated amortization for $670,000.