Final answer:
The correct suffix that best describes 'breathing' is pnea, which is commonly used in medical terms related to respiration.
Step-by-step explanation:
The correct suffix that best describes 'breathing' is pnea. This suffix is commonly used in medical terms related to respiration. For example, 'apnea' refers to the absence or temporary cessation of breathing, 'dyspnea' refers to difficult or labored breathing, and 'hyperpnea' refers to increased depth or rate of breathing.