29. Which of the following best describes animal
species that function as a “keystone” (line 35)?
A. They are a major factor in disease
prevention.
B. They are a food source for other animals.
C. They pollinate every plant species.
D. They are crucial in maintaining the
balance of their ecosystem.
E. They generate the oxygen in the
atmosphere.

A keystone species is a life form that characterizes a whole environment. Without its keystone species, the biological system would be emphatically unique or quit existing through.

Keystone species have low practical overt repetitiveness. This intends that assuming the species were to vanish from the environment, no different species would have the option to fill its natural specialty. The biological system would be compelled to profoundly change, permitting new and conceivably obtrusive species to populate the natural surroundings.

Any life form, from plants to parasites, might be a keystone species; they are not generally the biggest or most plentiful species in a biological system. Nonetheless, practically all instances of keystone species are creatures that impact food networks. The manner in which these creatures impact food networks differs from one natural surroundings to another.

Therefore Option(b) is correct.

Learn more about Keystone species here:

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