Some years ago industries had more freedom than they have now, and they did not need to be as careful as they must today. They did not need to worry a lot about the safety of the new products that they developed. They did not have to pay much attention to the health and safety of the people who worked for them. Often new products were dangerous for the people who used them; often conditions in the work place had very bad effects on the health of the workers.

　　Of course sometimes there were real disasters which attracted the attention of governments and which showed need for changes. Also scientists who were doing research into the health of workers sometimes produced information which governments could not ignore. At such times, there were inquiries into the causes of the disaster or the problems. New safety rules were often introduced as a result of these inquiries; however, the new rule; came too late to protect the people who died or who became seriously ill.

　　Today many governments have special departments which protect customers and workers. In the U. S., for example, there is a department which tests new airplanes and gives warnings about possible problems. It also makes the rules that aircraft producers must follow. Another department controls the foods and drugs that companies sell. A third department looks at the places where people work, and then reports any companies that are breaking laws which protect the health and safety of workers. Of course, new government departments and new laws cannot prevent every accident or illness, but they are having some good results. Our work places are safer and cleaner than before. The planes and cars which we use for travel are better. Producers are thinking more about the safety and health of the people who buy and use their products.

The main topic of the passage is ____.（　　）

• A.conditions in the work place
• B.the safety of the product
• C.changes in industrial production
• D.the safety and health of workers and customers