听力原文： When Iraqi troops blew up hundreds of Kuwaiti oil wells at the end of the Gulf W

ar, scientists feared environmental disaster. Would black powder in the smoke from the fires circle the globe and block out the sun？

Many said "No way. Rain would wash the black powder from the atmosphere. But in America, air sampling balloons have detected high concentrations of particles similar to those that were collected in Kuwait. Some oil didn't catch fire. It has formed huge lakes in the Kuwaiti desert. They trap insects and birds, and poison a variety of other desert animals and plants.

The only good news is that the oil lakes have not affected the underground water resources. So far, the oil has not been absorbed because of the hard sand just below the surface.

Nothing, however, stops the oil from evaporating. The resulting poisonous gases are choking nearby residents. Officials are trying to organize a quick cleanup, but they are not sure how to do it. One possibility is to burn the oil. Get those black-powder detectors ready.

What is the problem with the elm tree near Jackson Hall？

A．It has grown too tall for its designated space.

B．It may be diseased.

C．Its branches are being broken off.

D．It no longer hears from.