A normal diastolic blood pressure is less than 80 mmHg... Thus , option B is right ans.

Diastolic Blood Pressure
Diastolic blood pressure refers to the pressure in the arteries when the heart is at rest between beats. It is the bottom number in a blood pressure reading and is an important indicator of heart health.

Correct Answer Explanation
The correct answer is option B - 80 mm Hg. This is because diastolic blood pressure is typically around 80 mm Hg in a healthy individual. A normal diastolic blood pressure reading is considered to be below 80 mm Hg.

Understanding Blood Pressure Readings
- Blood pressure is typically recorded as two numbers, with the systolic pressure (top number) representing the pressure in the arteries when the heart beats, and the diastolic pressure (bottom number) representing the pressure when the heart is at rest.
- A blood pressure reading of 120/80 mm Hg is considered normal, with 120 being the systolic pressure and 80 being the diastolic pressure.
- High diastolic blood pressure (above 80 mm Hg) can indicate underlying health issues such as heart disease, kidney problems, or hypertension.
- Low diastolic blood pressure (below 60 mm Hg) can also be a cause for concern and may indicate conditions such as dehydration, heart problems, or hormonal imbalances.

Conclusion
In summary, a diastolic blood pressure of 80 mm Hg is considered normal and healthy. Monitoring blood pressure regularly is important for maintaining overall cardiovascular health and preventing potential complications.