Correct Option: D

When a tree has been cut down or felled, then it is relatively easy to work out its age by counting the growth or annual rings that can be seen on the sawnoff stump. Under the bark of a tree is a special tissue (called the cambium) which forms new cells so that the tree can grow. Differences in the rate at which cells are produced by this tissue give rise to the annual or growth rings. If conditions are good for growth (warm, regular rainfall) then the ring that is formed will be wider than that created in a year where the tree struggles for water, or it is cold. There is one ring for each year of a tree’s life.