Answer:
The correct answer is: b. Radiometric.
Step-by-step explanation:
Radiometric dating, or radioactive dating, is a method that is utilized to learn the age of materials such as rocks by comparing the known affluence of a naturally occurring radioactive isotope with its decay products, which are formed at known constant rates. This means that they understand how old a material is by looking at how fast its radioactive components decay.
Radiometric dating is used by setting geological timescales and thus, it supplies with a great amount of information about the date of fossils, among other things.