Answer: D. Henri Becquerel discovered principles of radioactivity, which led to the determination of the Earth's age.
Explanation:
Henri Becquerel discovered naturally occurring radioactivity in 1896, which lead to the recognition by Marie and Pierre Curie that compounds of radium produce heat, and that those naturally occurring radioactive elements in minerals in the Earth’s surface are enough to account for all seen heat flow. Later, Ernest Rutherford ´s disintegration theory provided the foundation for the numerical quantification of geologic time, and Strutt developed the first successful use of a radiometric method to the analysis of Earth elements, and it´s geologic time.
