The protection period of invention patents in China is () A.5 years B. 10 years C. 15 years D.20 years.

Answer: D [Hint] This question examines the term of protection of the invention patent.

Article 42 of the Patent Law stipulates: "The term of the invention patent right is 20 years, and the term of the utility model patent right and the design patent right is 10 years, both of which are counted from the date of application." Therefore, item D is correct.