Vienna was a rich city ______.

A．To understand Vienna, one must know its trade.
B．After World War I , about 7 000 000 people lived in Vienna.
C．Green woods, mountains and a large river surround Vienna and make it a beautiful city.
D．Vienna musicians did little to make Vienna a city of spirits.

A．the most beautiful city in Europe
B．so big that it doesn't belong to Austria
C．the richest capital in Europe now
D．a small capital of a large country