A、Britain. B、New York. C、India. D、Japan. D题目问根据这篇讲稿世界上哪个国家的城市人口最密集。文章最后提到了两个人口最为密集的城市——东京和横滨。这两个城市都位于日本，显然日本是城市人口最为密集的国家。

As city residents, we all think that we know what the word "city" means, but do we really (32) ? Here are some interesting facts.
    In Britain, a town of any size can be called a city, if it has a cathedral. So London today includes the two cities of London and Westminster, because both parts have a cathedral (33) . But a small place in North Wales called St. Asaph has a population of fewer than 4,000 and yet because it has a cathedral it is also called a city. on the other hand, Birmingham was so large that it was specially made into a city, even though it did not have a cathedral (34) .
    In the USA, "city" is simply a legal term, and it does not depend on the size or importance of the place. Confusingly, however, the US Census Bureau, an American government department that conducts official counts of the population, classifies any place with a population of over 2,500 as a city, no matter how far out in the countryside it is.
    The world’s most densely populated city is the area of Japan that includes Tokyo and Yokohama, which has an estimated 29,272,000 inhabitants (34) . But, in the future, it may well be replaced by a city in China or a city in India.
    So, what is a city? It all depends on where you live.