A staff assistant at Warrington Corporation recently determined that the first four units completed in a new manufacturing process took 1,000 hours to complete, or an average of 250 hours per unit. The assistant also found that when the cumulative output produced doubles, the average labor time declines by 40%. On the basis of this information, how many total hours would Warrington use if it produces a cumulative amount of 16 units?

a- 1200

b-150

c-90

d-1440

e- None are correct