Questions from 36 to 40 are based on the following passage: In addition to visible trade, which involves the import and export of goods, there is also invisible trade, which involves the exchange of services between countries.Transportation service across national boundaries is an important kind of invisible trade. International transportation involves different means of transport such as ocean ships, planes, trains, trucks and inland water vessels. However, the most important of them is maritime ships. When an export arranges shipment, he generally books space in the cargo compartment of a ship or charters a whole vessel. Some countries such as Greece and Norway have large maritime fleets and earn a lot by way of this invisible trade.Insurance is another important kind of invisible trade. In the course of transportation, a cargo is vulnerable to many risks such as collision, pilferage, fire, storm, exploration, and even war. Goods being transported in international trade must be insured against loss or damage. Large insurance companies provide service for international trade and earn fees for other nations’ foreign trade. Lloyd’s of London is a leading exporter of this service.Tourism is yet another important form of invisible trade. Many countries may have beautiful scenery, wonderful attractions, places of historical interest, or merely a mild and sunny climate. These countries attract large numbers of tourists, who spend money for traveling, hotel accommodations, meals, taxis, and so on. Some countries depend heavily on tourism for their foreign exchange earnings, and many countries are making great efforts to develop their tourism.The fourth type of invisible trade meriting attention is called immigrant remittance. This refers to the money sent back to home countries by people working in a foreign land. Import and export of labor service may be undertaken by individuals, or organized by companies or even by states. And this is becoming an important kind of invisible trade for some countries.Invisible trade can be as important to some countries as visible trade is to others. In reality, the kinds of trade nations engage in are varied and complex, often a mixture of visible and invisible trade.
How many types of invisible trade are mentioned in the passage（）
A．2
B．3
C．4
D．5
