Read 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.

Whales are the largest animals in the world, and the gentlest creatures we know. Although the whale is very huge, it is not hindered at all by its size when it is in the water. Whales have tails that end like flippers. With just a gentle flick, it can propel itself forward. The skin of a whale is so smooth that it does not create any friction that can slow the whale down. A whale’s breathing hole is located on the top of its head, so it can breathe without having to completely push its head out of the water. Whales are protected from the cold seawater by body fat that is called blubber.

Whales live in the ocean but, in terms of behaviours, they are more similar to humans than fish.

They live in family groups and they even travel in groups when they have to migrate from cooler to warmer waters. The young stay with their parents for as long as fifteen years. Whales are known not to desert the ill or injured members; instead, they cradle them.

When whales are in danger, there are people who go to great lengths to help them. One such case occurred in 1988, when three young whales were trapped in the sea. It was close to winter and the sea had begun to freeze over. Whales are mammals that require oxygen from the air, so the frozen ice was a great danger to them. All they had then was a tiny hole in the ice for them to breathe through. Volunteers from all over soon turned up to help these creatures. They cut holes in the ice to provide more breathing holes for the whales. These holes would also serve as guides for the whales so that they could swim to warmer waters.

Which of the following best describes the main idea of this passage?

In the twentieth century, drug markedly improved health throughout the world