[单项选择]
B
根据下面短文回答下列问题。
A lighthouse is a tall building. It has a big light at the top. It is usually built on a cliff (悬崖) or near a harbor (港湾). People on ships can see the light from far away. They know there is danger where the light shines (发光). They stay away from it.
The first lighthouse was built in Egypt long ago. It was over 100 meters high and was made of white stone. On the top floor were rooms with open windows. Fires were burning in the rooms at night to warn (警告) ships they were near the harbor.
Later, lighthouses were built in many places. Whole families lived inside them and made sure the oil light was burning.
Today lighthouses have electric lamps and even horns. There is no need for anyone to live in them as the light or horn can be controlled automatically.
A lighthouse is built ______.
A. to light up the harbor
B. to warn people working on the ship
C. to light up the ship
