The Average Diastolic Blood Pressure of a Group of Men $$\begin{array}{l}\mathrm{H}_{0}: \mu=96 \mathrm{mmHg} \\\mathrm{H}_{\mathrm{a}}: \mu<96 \mathrm{mmHg}\end{array}$$

The average diastolic blood pressure of a group of men suffering from high blood pressure is 96 mmHg. During a clinical trial, the men receive a medication, which it is hoped, will lower their blood pressure. After three months, the researcher wants to perform a hypothesis test to determine whether the average diastolic blood pressure of the men has decreased. The hypotheses are: $$\begin{array}{l}\mathrm{H}_{0}: \mu=96 \mathrm{mmHg} \\\mathrm{H}_{\mathrm{a}}: \mu<96 \mathrm{mmHg}\end{array}$$
Explain the meaning of a Type II error.

A) Concluding that $\mu>96 \mathrm{mmHg}$ when in fact $\mu<96 \mathrm{mmHg}$
B) Failing to reject the hypothesis that $\mu=96 \mathrm{mmHg}$ when in fact $\mu<96 \mathrm{mmHg}$
C) Failing to reject the hypothesis that $\mu=96 \mathrm{mmHg}$ when in fact $\mu=96 \mathrm{mmHg}$
D) Concluding that $\mu<96 \mathrm{mmHg}$ when in fact $\mu=96 \mathrm{mmHg}$