**Core Concept**
The question is testing the understanding of the pathophysiological mechanisms underlying hypoxemia following pulmonary thromboembolism. The correct answer lies in the understanding of how a pulmonary embolism affects gas exchange in the lungs.

**Why the Correct Answer is Right**
Pulmonary thromboembolism leads to hypoxemia due to the blockage of pulmonary arteries, which reduces blood flow to the alveoli. As a result, the ventilation-perfusion (V/Q) mismatch occurs, where areas of the lung are ventilated but not perfused, leading to inadequate oxygenation of the blood. The affected alveoli are unable to exchange oxygen and carbon dioxide efficiently, causing a decrease in oxygen levels in the blood.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not directly related to the pathophysiology of hypoxemia following pulmonary thromboembolism. While it may be a complication of the condition, it is not the primary mechanism by which hypoxemia occurs.
* **Option B:** This option is incorrect because it is not a direct consequence of pulmonary thromboembolism. While it may be related to the condition in a broader sense, it does not explain the immediate cause of hypoxemia.
* **Option C:** This option is not a direct result of the blockage of pulmonary arteries by a thromboembolism. While it may be a consequence of the condition, it is not the primary mechanism by which hypoxemia occurs.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the severity of hypoxemia following a pulmonary thromboembolism is directly related to the size and location of the embolus. Larger emboli that block larger pulmonary arteries can lead to more severe hypoxemia.

**Correct Answer: C. V/Q mismatch due to blockage of pulmonary arteries.**