Which process involves counting tree rings to determine a tree's age?

The process of counting tree rings to determine a tree's age is known as dendrochronology. This scientific method is based on the principle that trees grow a new ring each year, and the width of these rings can vary based on environmental conditions such as rainfall, temperature, and sunlight. By examining the pattern and number of these rings, researchers can accurately date the tree and infer past climatic conditions. Dendrochronology is not just about age determination; it also provides valuable data for ecological and climatic studies, making it a vital tool in environmental science.

Other options, while related to the measurement of time or dating, focus on different subjects. Paleontology studies prehistoric life primarily through fossils; chronometry involves the measurement of time but does not specifically pertain to tree rings; and geochronology is the study of dating Earth's geological features rather than the specific biological context of trees.