A study of the quality of the production process at a factory measured vitamin C in specimens of corn-soy blend. For a random sample size of 9 the mean vitamin C is 25.5 miligrams. The sample standard deviation (s) is 8.21, and we want to find a 95% confidence level for the mean vitamin C content. The 95% confidence interval is
A) 21.68 to 29.32
B) 16.32 to 34.68
C)23.80 to 27.20
D)20.42 to 30.59
e) none of the above