Read the passage below and choose the best answer among A, B, C or D for each question :

Once there were lots of pandas in the mountains of Western China. Today they are becoming extinct. The reason is that they cannot find enough food. Pandas eat bamboo leaves. They do not like another food. The bamboo grows very slowly. It can take 10 years for a bamboo to grow from a seed to a big plant. Some types of bamboo have seeds only once every 60 years. Pandas must wait many years for their food to grow. While the bamboo is growing, pandas do not have enough leaves to eat.

Farmers are using more and more of the land on the mountain side to grow food for man. The farmers cut down the bamboo. Bamboo leaves become less plentiful. Pandas can not find enough food to eat. They starve and die.

China and World Wildlife Fund (WWF) are trying to save the pandas. In 1979 they began to set up special parks where pandas live. Once such park is the Wolong Reserve in Sichuan. The Wolong Reserve has the highest number of pandas in the world. Scientists come here to study the panda’s eating and mating habits. By learning more about panda’s habits, scientists can save it from extinction.

Question: Why do farmers cut down bamboo trees ?