**Core Concept**
Cells most sensitive to hypoxia are those with high energy demand and low glycogen stores. This includes neurons, red blood cells, and cardiac myocytes, which rely heavily on oxidative phosphorylation for energy production.

**Why the Correct Answer is Right**
Neurons, in particular, are highly sensitive to hypoxia due to their high metabolic rate and limited ability to store glycogen. When oxygen levels drop, neurons are unable to produce sufficient ATP through oxidative phosphorylation, leading to cellular dysfunction and death. This is why hypoxia can cause rapid neuronal damage and is a key feature of various neurological disorders. The sensitivity of neurons to hypoxia is due to the high expression of hypoxia-inducible factor-1 alpha (HIF-1α), which triggers a cascade of cellular responses to low oxygen levels.

**Why Each Wrong Option is Incorrect**
* **Option A:** While cardiac myocytes are indeed sensitive to hypoxia, they are not the most sensitive cells. This is because cardiac myocytes have some ability to adapt to low oxygen levels through anaerobic glycolysis.
* **Option B:** Red blood cells are highly sensitive to hypoxia, but they are not the most sensitive cells. This is because red blood cells lack mitochondria and rely almost exclusively on anaerobic glycolysis for energy production.

**Clinical Pearl / High-Yield Fact**
In clinical settings, hypoxia can be detected through various methods, including pulse oximetry, arterial blood gas analysis, and imaging studies such as MRI or CT scans. Early recognition and treatment of hypoxia are crucial to prevent tissue damage and improve patient outcomes.

**Correct Answer:** C. Neurons.