Acidosis refers to which of the following?

• A. Blood pH above 7.45.
• B. Blood pH between 7.2 and 7.4.
• C. Blood pH around neutral.
• D. Blood pH below 7.35.

Answer: (D)

Acidosis means the blood is more acidic than normal, which shows up as a pH below 7.35. Normal arterial pH is about 7.35–7.45, so when the value drops under 7.35, acidity increases and acidosis is present. The option describing a pH below 7.35 is the best fit because it pins down the precise threshold at which acidemia occurs. The other choices don’t fit because pH above 7.45 indicates alkalosis, a range like 7.2–7.4 is too broad and includes values above 7.35 (not all of which are acidosis), and “around neutral” isn’t a defined, useful clinical boundary for acid-base disorders. Acidosis can arise from respiratory or metabolic disturbances that lower pH, but the defining feature remains a pH below 7.35.