UNIVERSITY ENTRANCE EXAMINATIONRead the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions that follow. Over a period of time, many habitats change with respect to the types of plants and animals that live there. This change is known as succession. Succession occurs because plants and animals cause a change in the environment in which they live. The first weeds and grasses that appear on a bare field, for example, change the environment by shielding the soil from the direct sunlight. As these plants spread, the ground surface becomes cooler and moisture than it was originally. Thus, the environment at the ground surface has been changed. The new surface conditions favour the spouting of the shrubs. As shrubs grow they kill the grasses by preventing light from reaching them and also build up the soil in the area. In addition, they attract animals that...