The ratio of the mass of U-238 to the mass of Pb-206 can be used to 1.
diagnose thyroid disorders
2.
diagnose kidney function
3.
date geological formations
4.
date once-living things

3)date geological formations

Explanation:

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.

it is b that is the answer.