Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbers blanks

Wild animals play an important part in the (1) ____ of nature and supply us with many important products. Birds and other small animals help (2) ____ insects. Wild animals provide food and hobby too. Furthermore, they (3)____ our surroundings more interesting. Uncontrolled hunting has destroyed a lot of wildlife and people have also harmed animals such as the passenger pigeon which disappeared completely.

Others including the whooping cranes, the blue whale and the American alligator are in danger of dying out. Sometimes it is necessary to keep animals from (4) ______ too plentiful. For example, rabbits and such rodents as ground squirrels and mice may cause great damage to crops if they are too abundant predators help hold down the population of their prey.

(1)_______