Final answer:
Carbon-14 is produced in the upper atmosphere and is used in radiocarbon dating to estimate the age of organic materials after they have ceased exchanging carbon with the environment.
Step-by-step explanation:
The production of carbon-14 (14C) occurs in the upper atmosphere when nitrogen atoms are bombarded by neutrons from cosmic rays. This process forms 14C, which eventually combines with oxygen to create CO₂ that is absorbed by plants and subsequently ingested by animals. An organism continually exchanges carbon-14 with its environment until it dies, at which point the 14C decays with a half-life of approximately 5730 years. This decay process is utilized in the method known as radiocarbon or carbon-14 dating to estimate the age of ancient organic materials.