The simple interest on a sum of money will be Rs.800 after 10 years. If the principal is trebled after 5 years what will be the total interest at the end of the tenth year?  Choose the correct choice:
A) 8981 B) 3799 C) 1200 D) 1600 E) 1732

Rationale: "p - - - 10 - - - - 800 p - - - 5 - - - - - 400 3 p - - - 5 - - - - - 1200 - - - - - - = > 1600 answer : d"
Answer: D