Anatomical dead space is
**Core Concept**
Anatomical dead space refers to the volume of the conducting airways, where gas exchange does not occur. This space includes the **trachea**, **bronchi**, and **bronchioles**.
**Why the Correct Answer is Right**
The correct answer is related to the volume of these conducting airways. Anatomical dead space is approximately 150 mL in adults, which is the volume of the airways that does not participate in gas exchange.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect as it doesn't specify the correct volume or components of anatomical dead space.
**Option B:** Incorrect as it is not related to the definition of anatomical dead space.
**Option C:** Incorrect as it refers to a different concept.
**Option D:** Incorrect as anatomical dead space does not include alveoli.
**Clinical Pearl / High-Yield Fact**
Remember that anatomical dead space is an important concept in respiratory physiology, as it affects the **ventilation-perfusion mismatch**.
**Correct Answer:** Correct Answer: D. 150 mL.