One cannot calculate the age of a tree by its annual rings if that tree is located in which of the following forests?
Tropical deciduous
Tropical evergreen
Temperate deciduous
Temperate evergreen
In temperate woody plants and in a few tropical trees, the activity of vascular cambium is seasonal and is seen only in the secondary xylem. The cambium is less active in autumn and more active in spring. Thus, in each year two zones of secondary xylem are formed and both can be easily demarcated. These two zones form an annual or growth ring. By counting the number of annular rings, it is possible to know the age of a plant. The tropical evergreen trees do not have these annular rings due to lack of major seasonal changes.
So, the correct answer is 'tropical evergreen'. Hence, the correct answer is option 2.