**Core Concept:** The question is testing the understanding of oxygen transport in the human body, specifically focusing on the role of hemoglobin and its binding affinity to oxygen.

**Why the Correct Answer is Right:** Hemoglobin is the primary carrier of oxygen in the blood. It has a higher affinity for oxygen at lower partial pressure of oxygen (pO2), which means that as the partial pressure of oxygen decreases, hemoglobin binds to oxygen more readily. This ensures that oxygen is released to the tissues when pO2 is low, such as in hypoxia (low oxygen levels in tissues). Normal pO2 in arterial blood is typically around 95-100 mmHg, which indicates sufficient oxygen levels in the blood.

**Why Each Wrong Option is Incorrect:**

A. Decreased hemoglobin concentration in the blood (anemia) would result in lower oxygen carrying capacity but maintaining normal pO2 in arterial blood is not related to this.
B. An increase in pO2 would lead to more oxygen binding to hemoglobin, causing a decrease in its availability for tissues, not an increase in oxygen carrying capacity.
C. An increase in hemoglobin affinity for oxygen (lower pO2) would result in less oxygen being released to tissues, not an increase in oxygen carrying capacity.
D. In hyperoxia (excess oxygen in tissues), the body would attempt to remove excess oxygen through increased respiratory rate and ventilation to prevent tissue damage, not increase oxygen carrying capacity.

**Clinical Pearl:** A decrease in oxygen carrying capacity of blood is associated with conditions like anemia, hypoxia, or hemoglobin abnormalities. Maintaining normal pO2 in arterial blood is crucial in ensuring adequate oxygen delivery to tissues.

**Correct Answer:** C. An increase in hemoglobin affinity for oxygen (lower pO2) would result in less oxygen being released to tissues, not an increase in oxygen carrying capacity. This is known as the Bohr effect and is an essential concept in understanding oxygen transport in the human body.