A sum of Rs 1440 is lent out in three parts in such a way that the interests on first part at 2% for 3 years, second part at 3% for 4 years and third part at 4% for 5 years are equal. Then the difference between the largest and the smallest sum is (a) Rs 200     (b) Rs 400     (c) Rs 460     (d) Rs 560