At what rate of compound interest per annum will a sum of Rs. 1200 become Rs. 1348.32 in 2 years Choose the correct option:
A) 3 %  B) 4 %  C) 5 %  D) 6 %  E) 7 %

Rationale: "explanation : let rate will be r % 1200 ( 1 + r / 100 ) 2 = 134832 / 100 ( 1 + r / 100 ) 2 = 134832 / 120000 ( 1 + r / 100 ) 2 = 11236 / 10000 ( 1 + r / 100 ) = 106 / 100 = > r = 6 % option d"
Answer: D