Read the passage and complete the sentences. Mark the letter A, B, C or D on your answer sheet.

Once there were lots of pandas in the mountains of Western China. Today they are becoming extinct. The reason is they cannot find enough food. Pandas eat bamboo leaves. They do not like another food. The bamboo grows very slowly. It can take ten 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 cannot 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 can live. One 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 pandas’ eating and mating habits. By learning more about the pandas’ habits, scientists can save them from extinction.

What does the word “They” refer to?