Breathing too fast (hyperventilation) can decrease levels of CO2 in the blood. This is known as: 

• A. Hypocapnia. 
• B. Hypoxemia. 
• C. Hyperinhalation. 
• D. Hyperpnea.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the key terms related to blood gases and breathing. Carbon dioxide (CO2) levels in the blood are tightly regulated by the respiratory system.
2. Step 2: Recognize that hyperventilation means breathing too fast or too deeply, which causes excessive expulsion of CO2 from the blood.
3. Step 3: Know that a decrease in CO2 levels in the blood is called hypocapnia. The prefix 'hypo-' means low, and 'capnia' refers to carbon dioxide.
4. Step 4: Differentiate hypocapnia from other terms: hypoxemia refers to low oxygen in the blood, hyperinhalation is not a standard medical term, and hyperpnea means increased depth and rate of breathing but does not specify CO2 levels.
5. Step 5: Conclude that the correct term for decreased CO2 levels due to hyperventilation is hypocapnia.