Final answer:
The most accurate method to determine the age of a fossil is by measuring the amount of radioactive elements present, using radiometric dating to calculate the precise age.
Step-by-step explanation:
To most accurately determine the age of a fossil, a scientist needs the amount of each radioactive element present in the fossil. This can be identified by using radiometric dating, a process that measures the decay of radioactive materials that is indicative of the fossil's age.
Radiometric dating works because radioactive materials decay at a known rate. By measuring how much of the radioactive material has decayed, scientists can establish the absolute age of the fossil. This information is essential for providing an approximate age in years, which is more accurate than methods such as comparing the age of the strata or the presence of index fossils.
While the thickness of the strata and the age of the strata beneath the fossil can provide relative dating information, they are not sufficient for an exact age determination. Radiometric dating, in contrast, can offer numerical ages by evaluating the ratio between parent and daughter isotopes and calculating how many half-lives have passed since the fossil was formed.