In basic botany, which feature of a tree allows us to determine its exact age with reasonable accuracy?

Introduction / Context:
This question belongs to general science and environmental studies. It asks how we can estimate or determine the age of a tree. Knowing the age of trees is important in forestry, climate research, and ecology. Competitive exams frequently ask this simple yet important concept to test whether candidates remember the scientific method known as dendrochronology.

Given Data / Assumptions:

The question asks which characteristic of a tree tells us its exact age.
Options mention height, trunk width, rings, and branches.
We assume we are talking about typical temperate trees that produce growth rings each year.
We also assume that we are using standard school level knowledge about tree anatomy.

Concept / Approach:
The scientific method of determining a tree's age is based on counting annual growth rings in the trunk. These rings form because trees grow more rapidly in some seasons and more slowly in others, creating visible bands. While height and width change with age, they are influenced by many other factors such as soil and climate, so they cannot give an exact age. Branches also vary and are not reliable indicators.

Step-by-Step Solution:
Step 1: Recall that when the trunk of a tree is cut crosswise, we can see a pattern of concentric circles. Step 2: Each visible ring generally corresponds to one year of growth in many tree species. Step 3: By counting these rings from the center outward, scientists and forest officers can estimate how many years the tree has been alive. Step 4: Height, trunk width, and number of branches can vary widely for trees of the same age, so they do not provide precise age information. Step 5: Therefore, rings of the tree are the correct feature to determine age.

Verification / Alternative check:
The field that uses tree rings to study time is called dendrochronology. It is used not only to find the age of trees but also to study past climates, droughts, and environmental conditions. Reference books and science lessons clearly mention that one ring usually equals one year of growth. This independent information confirms that the option about rings is correct.

Why Other Options Are Wrong:
Height of the tree depends on species, soil fertility, sunlight, water, and competition. Two trees of the same age can have very different heights. Width of the trunk also varies based on growth conditions and species; it suggests maturity but not exact age. Number of branches is even more unreliable, because branches can break, be pruned, or grow in different patterns depending on environment and damage.

Common Pitfalls:
Some students may think that a thicker trunk always means an older tree, but a fast growing species can be thick at a younger age. Others may picture a tall tree as very old without considering growth rate. Another mistake is not knowing that the rings are inside the trunk and are counted only when the trunk cross section is visible or when a special boring tool extracts a core sample.

Final Answer:
The exact age of a tree is determined by counting the rings of the tree in its trunk.