first one
Explanation:
I'm also backing up the first person comment so if you're still confused if you really don't wanna pick that answer I can tell you it's correct!k-12 by the way!
Absolute dating is also known as radiometric dating, including determining the age of the rocks or fossil. There are scientific claims that the current geological processes are carried out in the same way as in the past. Unstable elements that emit energy are radioactive elements, which then form new elements or isotopes. The amount of energy that radioactive elements emit during decomposition is measurable, and even act precisely as watches. Scientists can thus determine the absolute age of the rock. This process is known as radioactive or radiometric dating. Very often, Uranium-238 is used for this purpose.