Berry Co. purchases a patent on January 1, 2021, for $33,000 and the patent has an expected useful life of five years with no residual value. Assuming Berry Co. uses the straight-line method, what is the amortization expense for the year ended December 31, 2022?

a. $0.
b. $33,000.
c. $6,600.
d. $13,200.