The correct option is
D Radioactive carbon (C-14) contents
Carbon-14 is known for its radioactive properties and is commonly used today for the carbon dating method to determine the age of the fossils. The body of the living organisms is mainly composed of the hydrocarbons and after death there occurs decaying in which this carbon content is lost. The carbon content can be determined by measuring the amount of carbon left in the fossil.
Thus, the correct answer is option D.