【单选题】

Vegetarianism

A、strict vegetarian is a person who never in his life eats anything derived from animals. The main objection to vegetarianism on a long-term basis is the difficulty to getting enough protein, the body building elements in fooD、If you have ever been without meat or animal foods for some days of weeks(say, religious reasons) you will have noticed that you tend to get physically rather weak. You are glad when the fast is over and you get your reward of a succulent meat meal. Proteins are built up from approximately twenty food elements called "amino-acids", which are found more abundantly in animal protein than in vegetable protein. This means you have to eat a great deal more vegetable than animal food in order to get enough of these amino-acids.
A、great of the vegetable food goes to waste in this process and from the physiological point of view there is not much to be said in favor of life-long vegetarianism.The economic side of the question, though, must be considereD、Vegetable food is much cheaper than animal fooD、However, since only a small proportion of the vegetable protein is useful for body-building purposes, a consistent vegetarian, if he is to gain the necessary 70 grams of protein a day, has to consume a greater bulk of food than his digestive organs can comfortably deal with. In fairness, though, it must be pointed out that vegetarians claim they need far less than 70 grams of protein a day.Whether or not vegetarianism should be advocated for adults, it is definitely unsatisfactory for growing children, who need more protein than they can get from vegetable source’’s.
A、lacto-vegetarian diet, which includes milk and milk products such as cheese, can, however, be satisfactory as long as enough milk and milk products are consumeD、Meat and cheese are the best sources of usable digestible and next come milk, fish and eggs. Slow and careful cooking of meat makes it more digestible and assists in the breaking down of the protein content by the body. When cooking vegetables, however, the vitamins, and in particular the water-solube vitaminC, should be lost through overcooking. From the passage, we know that______.
A、to gain enough protein, one must consume much more vegetable food than animal food
B．cooking vegetables for long time makes it more digestible
C．milk is the best source of usable animal protein
D．the most common deficiencies in Western diets are those of vitamins