On January \(1, 2010,\) Dave invests \(70\%\) of his retirement savings in Antarctic large-cap stocks, \(20\%\) in Antarctic midcaps, and \(10\%\) in Antarctic small-caps. In \(2010,\) large-caps rise \(5\%,\) midcaps rise \(10\%,\) and small caps rise \(15\%\) in the Antarctic stock market; however, in \(2011,\) large-caps fall \(10\%\) and midcaps fall \(20\%,\) while small caps rise \(x\%\) in Antarctica. If on January \(1, 2012,\) Dave has the same total amount of retirement savings as he did two years before, then \(x\) is between

A. 10 and 20
B. 20 and 30
C. 30 and 40
D. 40 and 50
E. 50 and 60

Answer: D

Source: Manhattan GMAT