A certain sum invested for T years at 10% per annum Simple Interest amounts to Rs.400. The amount gets halved when the interest comes down to 4% per annum, the principal and time being the same. What is the principal and value of T?

A

T = 50 years; P = Rs.200/3

B

T = 50 years; P = Rs.200

C

T = 25 years; P = Rs.200/3

D

T = 50 years; P = Rs.100