If we observe carefully, we can find that most of the flowers in nature are red, orange an

d yellow. If we have seen a black flower, it is a chance in a million. People have made census (普查) to colors of more than four thousand kinds of flowers and discovered that only eight of them are black. Why？

As we know, sunlight is formed by seven different kinds of colored light. The wave length of each light changes, so the quantity of heat in each light changes, too. Flowers, especially their petals (花瓣) , are very weak and easy to the harm caused by high temperature. Black flowers can take in all the light waves, which cause the flowers to dry up in a high temperature. So the black flowers can hardly continue their lives. But red flowers, orange flowers and yellow ones can protect themselves from sunlight by reflecting (反射) the red light, orange light and yellow light, each of which has a large quantity of heat.

That is why red, orange and yellow flowers are very common in nature while black flowers are so unusual.

We can hardly find black flowers because ______.

A．they are easy to be eaten by animals

B．there are no black flowers in the world

C．the petals of black flowers are too strong

D．the light waves make the flowers dry up