Normal range of breathing rate per minute in an average adult person at rest is. A. 9-12B. 15-18C. 21-24D. 30-33

The correct answer is B. 15-18.
The breathing rate (also known as the respiratory rate) is the number of breaths a person takes per minute. The normal range of breathing rate in a healthy adult at rest is typically between 12 and 20 breaths per minute. However, the most commonly accepted normal range is 15 to 18 breaths per minute.
Factors influencing breathing rate:
1. Age: The normal respiratory rate tends to decrease with age. Children, for instance, breathe faster than adults.
2. Physical Condition: In physically fit individuals, the respiratory rate may be on the lower end of the normal range because their body is more efficient at oxygenating the blood.
3. Health Conditions: Conditions like fever, anxiety, or lung disease can cause an increase in respiratory rate, while conditions like sleep or relaxation may cause the rate to fall below the typical range.
Explanation of the options:
1. 9-12 (A): This is below the normal range for an average adult. It may be normal for a very relaxed person or during sleep, but it is generally considered slow for an awake adult at rest.
2. 15-18 (B): This is the correct range for an average adult at rest. Most healthy adults breathe between 12 and 20 breaths per minute, with 15 to 18 being a typical average.
3. 21-24 (C): This is above the normal resting range for an average adult. It may indicate mild tachypnea (faster-than-normal breathing), which can occur due to physical exertion, stress, or health issues.
4. 30-33 (D): This is significantly higher than the normal range and would generally indicate tachypnea, which is abnormally fast breathing. This could be a sign of respiratory distress or other health problems.
The normal respiratory rate for an average adult person at rest is typically between 15 and 18 breaths per minute, though the broader normal range is 12 to 20 breaths per minute.
Therefore, the correct answer is B. 15-18.