(单选题)6: One of the world＇s most deadly health problems is spreading to new places. The problem is heart disease and it is affecting more and more people in developing countries. For years heart disease has been the number one cause of death in most industrial nations. The heart disease has claimed more life than cancer, accidents or Aids. In the past in most developing nations fewer people died from heart disease. They died instead from diseases such as lung disease. Now the World Health Organization has warned that heart disease is increasing rapidly in almost every developing nation. Why? One reason is that people in developing nations are living longer. Another reason is that many people have changed the way they live. They now eat more fat and salt and eat fewer fruits and vegetables. They drink more alcohol and they smoke more tobacco products. More people also work in offices now. They sit at the desk all day. They do not get enough physical exercise. The World Health Organization is worried about the increase in heart disease in developing countries. It has called on health experts in these countries to learn more about the problem. What tone is the author using in stating the spreading of heart disease in the Third World?

A: Impressive

B: Commanding

C: Angry

D: Warning