The correct option is B Marble powder reacting with dilute HCl.
There are many factors which affect the rate of a reaction. The surface area of solids is one such factor which affects the rate of the reaction.
∙ The rate of reaction increases if the exposed surface area of the reactant is more.
∙ When we use the powdered form of reactants in place of a stone, piece or chip of reactants, the rate of reaction increases as the surface area exposed is more.
∙ Therefore, the rate of the reaction will be more in the case of marble powder reacting with dilute HCl.