In 1990, the Average Duration of Long-Distance Telephone Calls Originating $\mathrm{H}_{0}: \mu=9.3$

In 1990, the average duration of long-distance telephone calls originating in one town was 9.3 minutes. A long-distance telephone company wants to perform a hypothesis test to determine whether the average duration of long-distance phone calls has changed from the 1990 mean of 9.3 minutes.
Formulate the null and alternative hypotheses for the study described.

A) $\mathrm{H}_{0}: \mu=9.3$ minutes
$\mathrm{H}_{\alpha}: \mu<9.3$ minutes

B) $\mathrm{H}_{0}: \mu=9.3$ minutes
$\mathrm{H}_{\alpha}: \mu>9.3$ minutes

C) $\mathrm{H}_{0}: \mu=9.3$ minutes
$\mathrm{H}_{\alpha}: \mu \neq 9.3$ minutes

D) $\mathrm{H}_{0}: \mu \neq 9.3$ minutes
$\mathrm{H}_{\alpha}: \mu=9.3$ minutes