A stock has an average return of 11.4% and a standard deviation of 31%. Assuming stock returns are normally distributed, what range of this stock's returns would you expect to see approximately two-thirds of the time?

options:

A:-35.1% to 57.9%

B:-19.6% to 42.4%

C:-84.6% to 104.4%

D:-67.1% to 88.9%

E:-50.6% to 73.4%

Please show me the process in detail!