Vitamin D is necessary for health and growth. It is used by the body to form. strong bones

and teeth. That is why growing children need it.

Vitamin D is also called the sunshine vitamin. It forms when the skin is exposed to the sun. In the past people Blew what vitamin D was they learned that sunshine was important. Poor children lived in crowded slums (贫民窟). And they were often ill with tickets (软骨病) . In Englad a tax was once placed on windows. Builders put few windows in houses. Rickets became so common that it was called the English disease.

Because adults have reached full growth, they probably__________.

A．need as much vitamin D as children

B．need less vitamin D than children

C．need more vitamin D than children

D．need no vitamin