CASAS Level D Practice Test 2026 – Complete Forms 187R and 188R Prep

Relating to breathing is described by the term respiratory. It comes from the same root as respiration and is used in medical and everyday language to refer to anything connected with breathing, the lungs, airways, and the breathing process. You’ll see it in phrases like respiratory rate or respiratory system.

The other words don’t fit because their meanings are unrelated to breathing: blunt or obvious is “blatant,” something ordinary or typical is “run-of-the-mill,” and a person who buys and sells goods is a “merchant.”