Environmental groups and rock climbers are always at loggerheads because of the effect of rock climbing on the environment. There have been many examples, wherein rock climbers are accused of going into natural reserves and treating the animals, plants and rocks there badly. However, with the changing times, rock climbers are conscious and carry out minimal climbing.
  Rock climbers hammer bolts（螺栓） on climbing routes and in the process damage the nature of rocks. In addition, climbing activities also have an effect on the animals and plants situated near the climbing area.The plants growing near the base of rocks are trampled（踩踏），and the animals living in the climbing area are forced out of their places, whenever humans are around. For example, during the summer climbing season, pregnant females of an endangered species of snake live in open areas like roadsides, exposed walls or rocks, where there is less canopy closure（树冠郁闭） compared to areas occupied by non-pregnant females and males. According to climbers, these open areas are very ft for climbing during summer.
  Many rock climbers have understood the significance of wildlife plant and animal preservation and related issues, and therefore take measures to reduce effects on climbing areas. Considering the effect of climbing activities on natural reserves, various national parks and wildlife agencies have put forth certain regulations on climbers. There are seasonal closures of climbing areas to avoid illegal entrance of uninformed rock climbers.
  Climbers are always expected to support wilderness preservation Many environmental organizations have been formed to protect the environment and in the process draw up certain guidelines for rock climbers. Both sides have come to a common understanding of the effect of rock climbers on protected areas.



What does the underlined part "at loggerheads" in Paragraph 1 mean？ ______

A. In support.
B. In difficulty.
C. In disagreement.
D. In communication.

Why is the example of snakes mentioned in Paragraph 2？ ______

A. To show how special their living habits are.
B. To show rock climbing affects their lives.
C. To show climbers are exposed to great danger.
D. To show how to avoid wild animals in summer.

What do environmental organizations do to preserve wilderness？ ______

A. Give guidelines to rock climbers.
B. Accuse climbers of their climbing.
C. Close some secured natural reserves.
D. Encourage climbers to choose open areas.

What is the text mainly about？ ______

A. Efforts made to protect rock climbers.
B. The recent popularity of rock climbing.
C. Environmental issues of rock climbing.
D. Rock climbers' environmental awareness.