单项选择题

"Much of the sickness and death attributed to the major communicable (可传染的) diseases is in fact caused by malnutrition (营养不良) which makes the body less able to withstand infections when they strike," said Dr. Hiroshi Nakajima, Director-General of the World Health Organization (WHO). "At the same time," he added, "in developing countries today, malnutrition is the cause of 174 million children under five years of age being underweight, and 230 million being stunted in their growth. Such figures represent deprivation, suffering and wasted human potential on a scale that is unacceptable from every point of view. Whether we think in terms of humanitarian concern, common justice or development needs, they demand a response, both from national governments and from the international community. "
WHO, working closely with its member states, other United Nations agencies and nongovernmental organizations, is focusing on major crippling (致残的) forms of malnutrition, such as protein-energy malnutrition, vitamin A deficiency (缺乏，不足). At the end of January 1996, 98 countries had national plans of action for nutrition and 41 countries had one under preparation, in keeping with their commitments made at the International Conference on Nutrition in Rome December 1992. The global situation, however, remains grim. Over 800 million people around the world still cannot meet basic needs for energy and protein, more than two thousand million people lack essential micro-nutrients, and hundreds of millions suffer from diseases caused by unsafe food or unbalanced diets.
It is now recognized that 6. 6 million out of the estimated 12.2 million deaths annually among children under five—or 54% of young child mortality (死亡率) in developing countries—is associated with malnutrition In addition to the human suffering, the loss in human potential translates into social and economic costs that no country can afford. In 1990, only 53 developing countries had reliable data on the number of young children under weight; by 1995, 97 countries had such data, nearly all of which included information on stunting and wasting.
In some regions, such as sub-Saharan Africa and south Asia, stagnation of nutritional improvement combined with a rapid rise in population has resulted in an actual increase in the total number of malnourished children. Currently, over two-thirds of the world’s malnourished children live in Asia (especially south Asia). followed by Africa and Latin America. According to the writer, what is the worst thing caused by high young child mortality