B. Read the passage carefully, then choose the correct answer.

The World Trade Organization (WTO) has 150 member countries. They are looking to improve trade. The goal of the WTO is to make trade grow by removing legal barriers between countries.

The WTO helps trade in several ways. First, it asks countries to treat each other equally. They should not give special trade deals to one country and not to another. Also, these countries should not try to stop foreign products from any one country. The idea is that goods and services should be able to cross borders easily. A second way to improve trade is to lower tariffs. These are special taxes for things bought and sold. A third way to strengthen trade is to make sure that the rulers will stay the same. In order for people to invest their money, they need to feel secure for the future. A fourth way is to allow greater competition between countries. The central belief is that competition makes for a stronger economy. The last way to improve trade is to help countries that are poor. They need help coming up to the level of modern countries. They can be helped by allowing them extra time to get their systems in order. They can be given priority in making deals with other countries.

Free and easy trade is the WTO’s goal. It supports rich countries and helps poor countries to get ahead. Every year, more countries apply to be in the WTO.

and centres throughout the world. Most of the field offices are “cluster offices (51) ________three or more countries;