We have the value of population parameter p = 0.1
This means q = 0.9
Sample Size = n = 115
The formula for the standard deviation to be used is:
[tex]s= \sqrt{ \frac{pq}{n} } [/tex]
Using the values, we get:
[tex]s= \sqrt{ \frac{0.1*0.9}{115} } \\ \\ s=0.028[/tex]
So, option D gives the correct value of Standard Deviation of the normal curve