单项选择题

You will hear three dialogues or monologues. Before listening to each one, you will have time to read the questions related to it. While listening, answer each question by choosing A, B, C or D. After listening, you will have time to check your answer. You will hear each piece once only.
How much is the damage done to the United States each year by red ants

A. 3 billion dollars.
B. 4 billion dollars.
C. 5 billion dollars.
D. 6 billion dollars.