Which phrase describes the element carbon-14?

A-decays at an unknown rate

B-found in an organism's remains

C-forms from the breakdown of nitrogen-14

D-is measured to determine the age of sedimentary rocks

The correct option is B.

Carbon-14 is a carbon radioisotope discovered on february 27, 1940 by Martin Kamen and Sam Ruben.

It is used to determinate the age of fossils or archaelogical remains that contain organic material : remains of living beings or objects made of natural raw materials such as wood.

The radiocarbon dating method is the most reliable technique for knowing the age of organic samples less than 60.000 years old.

Paleontologists as they know the average time of disintegration of that isotope, examining the amount of that compound and its extinction curve, can know the antiquity of a fossil.

The mass of the 14C isotope of any specimen decreases at an exponential rate, which is known at 5.730 years after the death of a living being, the amount of 14C in its remains has been reduced by half. Thus, by measuring the amount of radioactivity in a sample of organic origin, the amount of 14C still remaining in the material is calculated. This way it can be dated the moment of the death of the corresponding organism.

The element of carbon-14 would be that B. It is found in the remains of organisms