Although much of the equipment used by dentists is thrown away after one use, many of the instruments used to clean teeth, fill cavities, and deal with impactions and other dental problems are made of steel and must be sterilized. A dentist is considering replacing his conventional steam sterilizer with a chemical sterilizer that cleans without rusting or corroding instruments. Because the dentist is already familiar with sterilizers, he is looking to find the best price possible on a chemical sterilizer. He is engaged in a .

He is engaged in a  Modified rebuy.

Explanation:

In the field of business, a modified rebuy can be described as a situation in which a person or an organization buys products with modifications in it. The buyer can either change the supplier or certain other elements of the products which they previously took.

The same phenomenon can be seen in the question. The dentists is modifying his products and may as well modify the supplier from which he buys the product depending on the price.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."