Compare this with what happens in the mass production of poultry:there are battery farms,for example,where thousands of chickens live crowded together in one building and are fed on food which is little better than rubbish.Chickens kept in this way are not only tastel ess asfood;they also（ ）eggs which lack important vitamins.

单选题

Compare this with what happens in the mass production of poultry:there are battery farms,for example,where thousands of chickens live crowded together in one building and are fed on food which is little better than rubbish.Chickens kept in this way are not only tastel ess asfood;they also（ ）eggs which lack important vitamins.

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单选题

This passage is concerned with ___.

答案解析