Answer:
Explanation:
C-14 is an isotope of Carbon that is radioactive in nature and used for various purposes in the research and some other fields.
It is used in carbon dating, carbon labeling, and some other way.
As carbon labeling, it has may important in the detection of biochemical reactions.
Since the mature upper leaf part are away from the treated parts so the least amount of C14 is detected in such a portion.