Whats the main idea of the news item？A．The launching of the space shuttle Discovery has be

Whats the main idea of the news item？

A．The launching of the space shuttle Discovery has been postponed.

B．The space shuttle Columbia has disappeared in a catastrophe.

C．NASA planned to lift off the space shuttle Discovery in May.

D．NASA scientists are concerned about space shuttle Columbia.

请帮忙给出正确答案和分析，谢谢！