Which term is represented by the suffix '-pnea'?

The suffix '-pnea' is derived from the Greek word 'pnea,' which translates to 'breathing' or 'respiration.' In medical terminology, this suffix is commonly used to describe various conditions related to breathing. For instance, terms like 'dyspnea' refer to difficult or labored breathing, while 'hypopnea' indicates shallow breathing. The use of '-pnea' focuses specifically on the act or process of breathing, which is why this choice is the correct answer.

In contrast, the other terms relate to different concepts; 'drooping' refers to a state of hanging down or sagging, which is not specific to respiration. 'Porous' pertains to the ability to allow fluids or gases to pass through, typically used in contexts like materials or tissue but not related to breathing. Lastly, 'excessive flow' generally refers to an increased amount of fluid or substance, which does not align with the function or process of breathing that '-pnea' represents.