A sum of money place at compound interest doubles itself in 4 years. In how many years will it amount to eight times itself?	Choose the most appropriate option:
A) 22	B) 18	C) 12	D) 88	E) 29
100 ---- 200 ---- 4   400 ---- 4   800 ---- 4   ------   12 years   Answer: 12
<result>C</result>
A sum of money place at compound interest doubles itself in 4 years. In how many years will it amount to eight times itself?