Ineed i can't chose between a or d how can the rate of a reaction be increased? increasing the temperature decreasing the amount of reactants having less surface area having a lower concentration of reactants

Increasing the temperature  

Step-by-step explanation:

Increasing the temperature gives the reacting molecules more kinetic energy.

More of the molecular collisions will have enough energy to get over the activation energy barrier and the reaction rate will increase.

B) is wrong. If you halve the amounts in the recipe for the experiment, the concentrations stay the same. There is no change in the rate of reaction.

C) is wrong. If you decrease the surface area of a solid, there will be fewer of its molecules at the surface to react. The rate of reaction will decrease.

D) is wrong. If you decrease the concentrations of the reactants, their molecules will be further apart. There will be fewer collisions per second, so the reaction rate will decrease.

your answer would be a. 12.5 kg