For Enzyme-Catalyzed Reactions,what Happens as the Concentration of the Substrate

For enzyme-catalyzed reactions,what happens as the concentration of the substrate is increased?

A) The rate continues to increase as substrate concentration increases.
B) The rate increases until it reaches a maximum,constant value.
C) The rate increases until it reaches a maximum,then the rate decreases.
D) The rate decreases with increasing concentration of the substrate.
E) The rate decreases until it reaches a minimum,constant value.