level1 mock exam 115题

An analyst collected the following data for an asset:
Possible Rate of Return (Percent)        Probability
-10%                                                   0.20
-5                                                        0.30
10                                                        0.40
25                                                        0.10
The variance of returns for the asset are closest to:
A. 121.
B. 188.
C. 213.

答案是A

但是我怎么看那个答案解释怎么不对，麻烦大家来看看这道题到底是怎么回事？