Answer: Most rocks do not contain organic material-most fossils are not organic anymore. One of the most common isotopes used in radiometric dating is uranium-235 or U-235. ... This makes it useful for dating rocks that are very old. Radioactive isotopes with short half-lives cannot be used for dating old rocks.
not 100% sure :/
Answer:
Most common differences might be long but it is what it is
Explanation:
The answer is A. There was more energy escaping into space than being trapped by the atmosphere