单项选择题

Health food is a general term applied to all kinds of foods that are considered more healthful than the types of foods widely sold in supermarkets. For example, whole grains, fried beans, and corn oil are health foods. A narrower (47) of health food is natural food. This term is used to (48) between types of the same food. Raw honey is a natural sweetener, (49) refined sugar is not. Fresh fruit is a natural food, but canned fruit, with sugars and other additives, is not.
The most (50) term of all and the narrowest classification within health foods is organic food, used to (51) food that has been grown on a particular kind of farm. Fruit and vegetables that are grown in gardens, that are (52) only with organic fertilizers, that are not sprayed with (53) insecticides (杀虫剂),and that are not refined after harvest, are organic foods. Meat, fish, dairy and poultry products from animals that are (54) only organically grown feed and that are not injected with hormones (荷尔蒙) are organic foods.
In choosing the type of food you eat, then, you have basically two choices: inorganic, processed foods, or organic, unprocessed foods. A wise decision should (55) investigation of the allegations that processed foods contain (56) , some of which are proven to be toxic (有毒的), and that vitamin content is greatly reduced in processed foods.

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