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.

THE SAVANNAH

The tourist looking at the African savannah on a summer afternoon might be excused for thinking that the wide yellow grass plain was completely deserted of life, almost a desert. With only a few small thorn trees sticking out through the veldt, there seems to be almost no place for a living creature to hide. However, under those trees you might find small steenbok, sleeping in the shade, and waiting for the night to fall. There may even be a small group of lions somewhere, their bodies exactly the same as the tall grass around them. In the holes in the ground a host of tiny creatures, from rabbits and badgers to rats and' snakes are waiting for the heat to finish. The tall grass also hides the fact that there may be a small stream running across the middle of the plain. One clue that there may be water here is the sight of a majestic Marshall eagle circling slowly over the grassland. When he drops, he may come up with a small fish, or maybe a grass snake that has been waiting at the edge of a pool in the hope of catching a frog. The best time to see the animals then, is in the evening, just as the sun is setting. The best time of the year to come is in late September, or early August, just before the rains. Then the animals must come to the waterholes, as there is no other place for them to drink. And they like to come while it is still light; so they can see if any dangers are creeping up on them. So it is at sunset, and after the night falls, that the creatures of the African veld rise and go about their business. 

Why do animals come to the waterholes while it is still light?