19. An enzyme-catalyzed reaction was carried out with the substrate concentration initially a thousand times greater than the Km for that substrate. After 12 minutes, 1% of the substrate had been to product, and the amount of product formed in the reaction mixture was 20 a separate experiment, 30 % as much enzyme and twice as much substrate had been combined, how long would it take for the same amount of product to be formed? (A) 6 min (B) 12 min (C)40 min (D) 18 min (E) 4 min