Choose your answer from:
(a). Twin towns exchange newspapers and stamps.
(b). Twin towns exchange business skill.
(c). Schools in twin towns exchange classes for a period of time.
(d). Ordinary people travel to the twin town.

Read the following article and answer the question. Article: In Europe, many people make friends between their countries through town twinning. Town or city twinning means two towns in different countries agree and decide to become "twins" with a sister-city relationship. The people find pen friends in the twin town. They exchange newspapers and stamps. The school teachers discuss teaching methods with the teachers in the twin town. Officials visit the twin town for celebrations. Ordinary people travel to the twin town, too, but not very often if it is far away. Sometimes, schools even exchange their classes for two or three weeks! For example, German middle school students study for a while at the school in their twin town in Britain, staying with British families. A few months later, their British friends come to study in Germany. Many British towns are so pleased with the results of the twinning that they set out to find more than one twin town! Tonbridge, a small town in Kent, for example, has twin towns in both Germany and France. Richmond near London has relationships with Germany, France and even a town in a Balkan country! Town twinning can help make friends. It helps students improve their language skill, and also helps people to understand the differences between nations. Question: Which of the following is NOT mentioned in the passage? Answer:
Answer:
(b).