Answer:
c. peak flow meter
Step-by-step explanation:
A peak flow meter is a portable device that helps measure the lungs ability to expel air. It calculates the maximum expiratory flow rate which is a measure of how rapidly air can be exhaled from your lungs, after taking a deep breath. This gives an idea about how good air is moving through the airways.
In cases like asthma-related bronchoconstriction, peak flow levels will be low. Maximum flow measurements help at regular intervals to keep up with the level of asthma control by detecting airway narrowing before symptoms occur.