A sum of money lent out at compound interest increases in value by 50% in 5 years. A person wants t lend three different sum x, y and z for 10, 15 and 20 years respectively at the above rate in such way that he gets back equal sums at the end of their respective periods. The ratio x : y : z is = ?

• A. 6 : 9 : 4
• B. 9 : 4 : 6
• C. 9 : 6 : 4
• D. 6: 4 : 9