(阅读理解) New York City New York City is the world's greatest city for walking in. All five borough(区）can be explored on foot, but Manhattan is probably the easiest and most popular for pedestrians and visitors. All the streets north of Houston Street go from east to west and all the avenues go from north to south. The streets are numbered low to high going north. The avenues are numbered low to high going west. Twenty "street" blocks (e.g. 40th to 60th Street）is one mile（1.6 km) and usually takes 20 to 30 minutes to walk. Walking is best for people who want to see more - the architecture, the people, and the street life. If you walk around New York City, there is a good chance you will walk past movie stars, television stars, music stars and models, but you might not notice them. If you are going to walk, and you don't want to get lost, ask locals for directions. Most New Yorkers love giving directions. "Tell us where you want to go. We will gladly help you, but we're always in a hurry！Don't take it personally if we just say，'3 blocks that way,' and keep walking."（单选题）Which city is the world's greatest city for walking in?
选项：

A:New York City.
B:Tokyo.
C:London.
D:Sydney