Reena took a loan of $. 1200 with simple interest for as many years as the rate of interest. If she paid $ 300 as interest at the end of the loan period, what was the rate of interest? Pick one:
A) 5 B) 6 C) 18 D) can not be determined E) none of these

Rationale: "let rate = r % and time = r years . then , 1200 x r x r / 100 = 300 12 r 2 = 300 r 2 = 25 r = 5 . answer : a"
Answer: A