Aptitude question

Complete this series 96, 320, 800, 1600, ?
1.640
2.2666.7
3.2500
4.2400
5.None of these

4. How much time will it take for an amount of Rs. 450 to yield Rs. 81 as interest at 4.5% per annum of simple interest?

A. 3.5 years B. 4 years
C. 4.5 years D. 5 years