What is the normal range for an adult's respiratory rate?

The normal range for an adult's respiratory rate typically falls between 12 to 20 breaths per minute, with 12 to 16 breaths per minute often considered optimal for many healthy adults. Therefore, the choice stating 10-20 breaths per minute is the closest to this generally accepted range.

In this context, while the lower end of the selected range (10 breaths per minute) may be on the cusp of what's considered normal and could be seen in some individuals at rest or in controlled conditions, the upper limit of 20 breaths per minute is still acceptable within the standard medical parameters.

The other options exceed the usual normal range for adults, indicating potential signs of health issues or necessary additional medical evaluation. Breathing rates above 20 breaths per minute may suggest conditions such as anxiety, exertion, or respiratory distress, which are typically not reflective of normal, healthy respiratory function in resting adults.