How Is the Accounting Treatment Different for Purchased Intangible Assets

How is the accounting treatment different for purchased intangible assets as opposed to internally-generated intangible assets?

A) Internally-generated assets are amortised over a shorter useful life
B) Cost is recorded gradually for internally-generated intangible assets but at acquisition for purchased assets
C) Act of registering patents is more detailed for an internally-generated intangible asset
D) There are no differences in the accounting treatment for purchased or internally generated intangible assets