听力原文：W: There are too many private cars on the road now, which causes traffic congestion and also pollution. I think the way to solve the problem is to improve our public transport--more buses, more railways, more shared taxis. Don't you think so？
M: Well, you're obviously not aware the government is spending money on some forms of public transport. For example, some train services have been improved. But most people want to use their cars, so the government needs to spend most money on improving the roads.
W: Why not make people who use the roads pay a bit more to discourage people from using their cars？
M: I really can't agree with you there. It just isn't fair to make driving something that only rich people can afford. Many people need to use their cars and they're dependent on them, particularly those in the country.
W: Can we do something to make people stop using their cars？
M: In a modem society you just can't do so. The whole economy would collapse.
W: So your opinion is...
M: To improve roads will help people get to work faster, so people spend less time in their cars and of course this therefore causes less pollution. That's the only realistic answer.
(23)

A. Too many private cars.
B. Too many buses.
C. Too many trains.
D. To many taxis.