Which statement best predicts the activity of an enzyme-catalyzed reaction as the concentration of substrate in a sealed flask decreases? a. the rate of the reaction will increase. b. the rate of the reaction may increase or decrease. c. the rate of the reaction will decrease. d. the rate of the reaction will not change.

The correct option is C.
In a chemical reaction, enzymes usually work on the substrates and speed up their rates, so that the reaction will occur faster. When the concentration of the substrate is high, the enzyme will work optimally, but when the substrate concentration decrease, the enzyme activity too will decrease, because it has less substrate to work on.

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