Use the Following to Answer the Question(s) Below

Use the following to answer the question(s) below.
IT staff for a large corporation has developed the following probability distribution for the number of calls requiring troubleshooting problems per day.
Number of Calls Probability
0 0.32
1 0.35
2 0.18
3 0.10
4 0.05
-The standard deviation in the number of calls per day is

A) 1.31
B) 1.14
C) 2.77
D) 1.56
E) 1.21