willsucceed

An analyst gathered the following information about a common stock:
Probabilit………….Possible Rate of Return
0.35……………………..8%
0.3……………………………10%
0.25……………………….15%
0.1………………………20%
The expected return and expected standard deviation of returns, respectively, for the common stock are closest to:
A. 12% and 3.9%.
B. 12% and 15.3%.
C. 14% and 3.9%.
D. 14% and 15.3%.
Not getting the Standard deviation..anser is A