George is an investor who believes that past variability of stocks is a reasonably good estimate of future risk associated with the stocks. Gerge works on creating a new portfolio and has already purchased stock A$.$ Now he considers two other stocks, B and C$.$ George collected data on the historic rates of return for all three stocks, which are presented in the following table.

$\backslash$table$[[$Year$,$Stock A$,$Stock B$,$Stock C$],[2015,30\%,25\%,-10\%$