Completing the sentence 1. in large areas of the huge swamp, there were pools of water covered with unmoving masses of green slime

a

explanation:

the answer is industry

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a constant variable, normally called a controlled variable, is the term for a variable that remains constant throughout an experiment, though other variables may change. an example is the water pressure for a faucet when measuring the amount of water released when the faucet is opened to various increments.