The following text is for questions 36 to 40.

    Sean and Mark Saunders joined a tour to South Africa. There were eight tourists in the group and two National Park guards. 

    Early in the morning, the group arrived at the park. It was a beautiful and peaceful morning. They started their journey on a path near a small river. Along the way, they saw many kinds of animals roaming about, such as African buffaloes, elephants, and giraffes. Those animals drank from the river and then walked away.

    Suddenly, Sean saw a black rhino among the bushes. He told the group. The tourists were so excited to see the rare animal. They took pictures of the animal, which was only a hundred meters away. Then the guards realised that it was a male rhino and it was a bit nervous by the tourists' presence on its territory. The guards made some noise by yelling and hitting their guns with their hands to scare the animals.

    However, their efforts didn't work well. The action made the male black rhino angry. It charged towards the group. It was ready for a fight. Sean, who was very close to the animal, was its first target. The rhino struck him powerfully with its horn on his left leg. The rhino then turned to Mark who was trying to save his brother. The rhino hit Mark's chest. It broke some of Mark's rib bones.

    One of the guards, then, animed his gun at the rhino before it made another attack. He shot the rhino in its belly. The wounded animal escaped to the bushes.

36. Why did the rhino feel disturbed?