What is the rate percent when the simple interest on Rs.800 amount to Rs.128 in 4 Years? Choose the correct option:
A) 5 %	B) 3 %	C) 4 %	D) 9 %	E) 1 %

Rationale: "128 = ( 800 * 4 * r ) / 100 r = 4 % answer : c"
Answer: C