B. This is because there were still active sites available for the starch substrate to bind to when the concentration was initially increased (the reaction will have been first order with respect to the concentration of starch). However, at a certain concentration, all the active sites of the enzymes will be full so there will be no active sites available for the starch molecules to bind to (the reaction is now zero order with respect to the concentration of starch). i need brainliest answer to rank up plzzzz help