I believe it would be to calculate the amount of C-14 atoms left. scientists began to find out how long an object has been decaying, this has to do with half lifes etc. and how long a specific mineral/elements half life is. they use this to calculate how old it is (not an exact age but it's very accurate.)
Answer:
This statement is true, as the inner core is the most dense layer of the earth.
The correct answer is dynamo theory. The theory that explains the source of Earth's magnetic field is the dynamo theory. This theory proposes the mechanism of a celestial body such as Earth to generate magnetic field.
I would say A, B D are the correct answers