The correct answer is: D. None of these
A patent account is an intangible asset. Intangible assets are assets that do not have physical substance, but have value because of the rights or privileges they convey. Patents are a type of intangible asset that give the owner the exclusive right to make, use, or sell an invention for a certain period of time.
Investments are assets that are held for the purpose of generating income or capital appreciation. Liabilities are obligations that a company owes to its creditors. Current assets are assets that are expected to be converted into cash or used up within one year.
Therefore, a patent account falls under the category of intangible assets.