**Core Concept**
The question is testing the understanding of lung physiology, specifically the **pulmonary capillary volume**. This concept is crucial in comprehending gas exchange and respiratory function. The **pulmonary capillaries** play a vital role in facilitating the exchange of oxygen and carbon dioxide between the lungs and the bloodstream.

**Why the Correct Answer is Right**
The correct answer choice is related to the average volume of blood in the pulmonary capillaries, which is approximately 100-150 milliliters (mL) in a healthy adult. This volume is critical for efficient gas exchange, as it allows for the optimal diffusion of oxygen into the blood and carbon dioxide out of the blood. The **pulmonary capillary bed** is a complex network of tiny blood vessels that facilitate this exchange.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately represent the average volume of blood in the pulmonary capillaries.
**Option B:** This option is also incorrect as it overestimates the volume.
**Option D:** Similarly, this option underestimates or overestimates the volume, depending on the actual values provided in the options.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the **pulmonary capillary volume** can be affected by various factors, such as posture, exercise, and disease states. Understanding these factors is crucial in diagnosing and managing respiratory conditions.

**Correct Answer:** Correct Answer: C. 150 ml