The cost of the purchased patent is capitalized in Patents account as an intangible asset. This cost is amortized over the years of the patent’s expected useful life. Intangible assets are generally amortized by straight-line method. The cost of the intangible asset is distributed to its useful life equally. In the first example, the useful life of the patent is 10 years.

So the amortization rate will be;  Amortization Rate=1/ Patent’ s Useful Life= 1/ 5

Amortization Expense = Capitalized Cost x Amortization Rate 

The correct answer is A.