Choose the appropriate test for the following situation. A company has instituted a new work policy that it hopes will reduce the number of sick days used per year by its employees. You wish to test whether the mean number of sick days used by employees this year differs from the mean number of sick days used last year by all employees (which was 8.2).
a. Two-sample t-test
b. One-sample t-test
c. Two-sample prop z-test
d. Dependent sample t-test