This graph shows how the reaction rate of a chemical reaction changed as the concentration of a reactant changed. Which sentence best describes how the reaction rate changed? 0.020 0.015 Reaction rate 0.010 0.005 0 10 0.2 0.4 06 0.8 Concentration of reactant O A. It gradually increased as the concentration of the reactant increased O B. It gradually increased as the concentration of the reactant decreased. O C. It suddenly decreased as the concentration of the reactant increased O D. It suddenly decreased as the concentration of the reactant decreased