It takes a long time to grow a tree. How long Well, pine trees are the quickest growing trees, but still, they take twenty years to reach a size suitable for cutting and harvesting. An oak takes about sixty years to grow to a good size. A redwood may take hundreds of years.
Lumber companies, which make their money on trees, depend on those that grow quickly. There- fore, they are always looking for methods to make trees grow faster. So far, the secret to fast growing trees seems to lie in "super-seeds." These are seeds that are gathered from the quickest growing trees in a forest. One company searched 100,000 acres of trees and selected the seeds from just fifteen trees. These two ounces of seed were enough to plant several hundred new trees. Eventually, when these trees have grown, seeds will again be taken only from the fastest growing trees of crop. This process of artificial selection will yield, in the future, a super-tree that will grow in half the time it
A. speech is beginning
B. conclusion follows
C. comparison is being made
D. metaphor is being used
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