W: Hello, it's me!
M: Yes, Ms...
W: I'm Mrs. Ernie Smelt. I want to make a complaint.
M: Yes, please.
W: I have been living near the Dulles International Airport for five years and there has always been a noise problem caused by airplanes taking off and landing.
M: That's really terrible. And five years is a long time.
W: Yes, but that's not the worst. The Super Sonic Transport Jets are allowed to land at Dulles the noise has become intolerable. We would like to sell our house and move to a quieter place but we can't find a buyer because no one could bear that noise.
M: I see, that's really very difficult to solve because it's the problem of both the Environmental Protection Agency and the Federal Aviation Administration, but the final authority in this matter belongs to Congress.
W: Do you mean that I should write a letter to the representatives of the Congress？
M: Yes, my suggestion is to each and every one of you listening to our program today to help by writing a letter, if you are brave enough, to tell them your problems.
W: Will it work？
M: Why don't you give it a try before giving up hope？
W: Thank you very much.
(20)

A. Litter.
B. Water pollution.
C. Air pollution.
D. Noise pollution.