A sample of 32 boxes of cereal has a sample standard deviation of 0.81 ounces. Construct a 95% confidence interval to estimate the true standard deviation of the filling process for the boxes of cereal.

a. (0.656, 1.064)
b. (0.520, 1.100)
c. (0.430, 1.132)
d. (0.729, 0.729)
e None of the above