Direction: A passage is given with question following it. Read the passage carefully and choose the best answer to each question out of the four alternatives.
As the rulers of the planet, humans like to think that it the large creatures who will emerge victorious from the struggle for survival. However, nature teaches us the opposite: it is often the smallest species which are the toughest and most adaptable. A prefect example is the hummingbird, which is found in the America. One species of hummingbird known as the bee hummingbird ranks as the world’s smallest and lightest bird and it is rarely visible when it is in flight. Humming birds are the only birds that can fly backwards. They feed mainly on the nectar of flowers, a liquid that is rich in energy. Nectar is an ideal food source, for hummingbirds. They need an incredible amount of energy to sustain their body metabolism. A hummingbird’s wings flap at a rate of  about 80 times per second and its tiny heart beats more than 1000 times per minute. This is why they must consume relatively large quantities of food. In the course of a day, a hummingbird consumes about half its body weight in nectar. Nature has made man realise the fact than: