A Sample of 100 Observations Has a Standard Deviation of 25

A sample of 100 observations has a standard deviation of 25 and a mean of 75. What is the 95% confidence interval?

A)
$50 \leq \bar{x} \leq 75$
B)
$73 \leq \bar{x} \leq 77$
C)
$70 \leq \bar{x} \leq 80$
D)
$74.5 \leq \bar{x} \leq 75.5$