下列哪一种细胞不表达HLAⅡ类抗原（）。

A.B细胞

B.T细胞

C.单核-巨噬细胞

D.树突状细胞

E.精子

Industrial pollution is not only a problem for the countries of Europe and North America but also an extremely serious problem in some developing countries. For these countries, economic growth is a very important aim. They want to introduce industries, and so they put few controls on the industries which cause pollution.
Cubatao, an industrial town of 85 000 people in Brazil, is an example of the connection between industrial development and pollution. In 1954, Cubatao had no industry. Today it has more than twenty large factories, which produce many pollutants. The people of the town are suffering from the poisonous matter in their environment and the bad effects can be clearly seen. Birth shortcomings are extremely common. Among children and adults, lung problems are sometimes twelve times more common in Cubatao than in other places.
It is true that Brazil, like many other countries, has laws against pollution, but these laws are not enforced strictly enough. It is cheaper for companies to take no notice of the laws and pay the fines than to buy the expensive equipment that will reduce the pollution. It is clear, therefore, that economic growth is more important to the government than to the health of the workers. However, the responsibility does not completely lie with the Brazilian government. The example of Cubatao shows that international companies are not acting in a responsible way either. A number of the factories in the town are owned by large companies from France, Italy, and the US. They are doing things in Brazil that they would not be able to do at home. If they caused the same amount of pollution at home, they would be severely punished or even put out of business.

Why do some foreign companies like to set up their plants in Brazil

A. The investment environment in Brazil is suitable for them.
B. They will not be severely punished if they cause pollution in Brazil.
C. They can make much money because they do not have to pay Brazilian workers much.
D. They can act in an irresponsible way in Brazil because there are no pollution laws there.