**Core Concept**
Pulmonary circulation differs from systemic circulation in terms of blood pressure, resistance, and oxygenation. The pulmonary circuit is characterized by low resistance, low pressure, and high oxygen levels, whereas the systemic circuit is marked by high resistance, high pressure, and varying oxygen levels.

**Why the Correct Answer is Right**
The key difference lies in the pulmonary vasculature, which has a lower vascular resistance due to the presence of pulmonary arteries and veins with thinner walls and smaller diameters. This allows for easier blood flow and lower pressures in the pulmonary circuit. Additionally, the pulmonary capillaries are highly permeable, allowing for the exchange of oxygen and carbon dioxide with the alveoli. In contrast, the systemic capillaries have thicker walls and are less permeable, facilitating the exchange of oxygen and nutrients with tissues.

**Why Each Wrong Option is Incorrect**
**Option A:** This option does not accurately describe the difference between pulmonary and systemic circulation. While it mentions the presence of capillaries in both circuits, it fails to highlight the unique characteristics of the pulmonary vasculature.
**Option B:** This option is incorrect because it does not specify the key differences between pulmonary and systemic circulation. The presence of a "pulmonary circuit" is not sufficient to explain the distinct features of the pulmonary vasculature.
**Option C:** This option is incorrect because it mentions the "high oxygen levels" in the pulmonary circuit, which is a characteristic of the systemic circuit, not the pulmonary circuit.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the pulmonary circuit has a unique set of characteristics that distinguish it from the systemic circuit. This includes lower vascular resistance, lower blood pressure, and high oxygen levels, which are crucial for gas exchange in the lungs.

**Correct Answer:** C.