**Core Concept**
The normal pH of blood is a critical parameter that reflects the acid-base balance in the body. It is regulated by the buffering system, which involves the equilibrium between hydrogen ions (H+) and bicarbonate (HCO3-) ions in the blood. The pH of blood is maintained within a narrow range of 7.35 to 7.45, with a mean value of approximately 7.40.

**Why the Correct Answer is Right**
The pH of blood is measured on a scale from 0 to 14, with 7 being neutral. A pH of 7.4 is slightly alkaline, which is necessary for proper functioning of enzymes and proteins in the body. The buffering system in the blood, which includes hemoglobin, phosphates, and bicarbonate, helps to maintain this pH range by absorbing excess hydrogen ions. This is achieved through the reaction of hydrogen ions with bicarbonate ions to form carbonic acid, which is then converted to carbon dioxide and water.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we cannot comment on it.
**Option B:** This option is not provided, so we cannot comment on it.
**Option C:** This option is not provided, so we cannot comment on it.
**Option D:** This option is not provided, so we cannot comment on it.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that a pH of 7.30 is considered acidosis, and a pH of 7.50 is considered alkalosis. A pH of 7.40 is the normal range, and any deviation from this can lead to various clinical manifestations.

**Correct Answer: 7.40**