This topic mainly investigates the object of patent right. Paragraph 1 of Article 25 of the Patent Law stipulates: "No patent right shall be granted for the following items: (1) scientific discovery; (2) rules and methods of intellectual activities; (3) Methods of diagnosis and treatment of diseases; (4) Species of animals and plants: (5) substances obtained by nuclear transformation: (6) designs mainly used to mark patterns, colors or the combination of the two in plane printed matter. " Therefore, A is a scientific discovery, so it can't apply for a patent and won't be elected. Item C belongs to the diagnosis and treatment of diseases, so it cannot be patented, so it is not selected. Both B and D can be patented or elected.