We can slow down aging. That is the message Dr. Shen Ziyin wants to give the world. And the Chinese doctor claims that he has found an answer to the problems of aging. His solution is a herbal medicine to slow the process of aging. Dr. Shen Ziyin has been trained in Western medicine. At the same time he studied traditional Chinese medicine. And, he has been working for the past forty years to put together the best of both and find a cure for aging. He has taken a hint from the ancient Chinese medicine system called "Shen". According to Shen, it is the kidney which adjusts the functioning of the body as well as its aging process. It is responsible for the level of activity that the human bodies go through. Studies conducted by Dr. Shen show that herbal medicine based on the Shen system slows the aging process, says a report in the Telegraph newspaper. We notice that when people grow old, they have reduced strength, loss of hair, backache, weakness, wrinkles and so on. This happens because when people grow old, their bodies produce T-cells. These T-cells contain a particular substance called Fas. Fas makes the cells in the body destruct themselves. So the only way to slow down aging is to slow the production of T-cells in the body. This can happen if people eat low calorie food. Then the body is not active enough to produce extra T-cells. But, is going hungry all the time a good price to pay for staying young? This is where Dr. Shen's herbal medicine comes in. But how effective it will be, only time can tell. The reason why people become old is that  _  .
their bodies produce T-cells they become weaker and weaker they have reduced strength, loss of hair their bodies are unable to fight diseases
Question: We can slow down aging. That is the message Dr. Shen Ziyin wants to give the world. And the Chinese doctor claims that he has found an answer to the problems of aging. His solution is a herbal medicine to slow the process of aging. Dr. Shen Ziyin has been trained in Western medicine. At the same time he studied traditional Chinese medicine. And, he has been working for the past forty years to put together the best of both and find a cure for aging. He has taken a hint from the ancient Chinese medicine system called "Shen". According to Shen, it is the kidney which adjusts the functioning of the body as well as its aging process. It is responsible for the level of activity that the human bodies go through. Studies conducted by Dr. Shen show that herbal medicine based on the Shen system slows the aging process, says a report in the Telegraph newspaper. We notice that when people grow old, they have reduced strength, loss of hair, backache, weakness, wrinkles and so on. This happens because when people grow old, their bodies produce T-cells. These T-cells contain a particular substance called Fas. Fas makes the cells in the body destruct themselves. So the only way to slow down aging is to slow the production of T-cells in the body. This can happen if people eat low calorie food. Then the body is not active enough to produce extra T-cells. But, is going hungry all the time a good price to pay for staying young? This is where Dr. Shen's herbal medicine comes in. But how effective it will be, only time can tell. The reason why people become old is that  _  .
A. their bodies produce T-cells
B. they become weaker and weaker
C. they have reduced strength, loss of hair
D. their bodies are unable to fight diseases
Answer: