**Core Concept:** Hemoglobin is a protein found in red blood cells that plays a crucial role in transporting oxygen in the human body. When fully saturated, hemoglobin can bind and carry a specific volume of oxygen.

**Why the Correct Answer is Right:** One gram of hemoglobin, when fully saturated, can combine with and carry 170 milliliters of oxygen. This is because hemoglobin has four binding sites, each capable of binding with one molecule of oxygen. In the fully saturated state, each site is occupied, resulting in the total capacity of 170 milliliters.

**Why Each Wrong Option is Incorrect:**

A. 100 ml (incorrect) - Hemoglobin's oxygen-carrying capacity is not limited to 100 milliliters.
B. 200 ml (incorrect) - The actual capacity is 170 milliliters, making this choice incorrect.
C. 300 ml (incorrect) - As explained above, the correct capacity is 170 milliliters, making this option incorrect.
D. 400 ml (incorrect) - The actual capacity is 170 milliliters, making this choice incorrect.

**Clinical Pearl / High-Yield Fact:** The oxygen-carrying capacity of hemoglobin is essential for understanding the hemodynamic response in various clinical scenarios, such as during hypoxia, where an increase in hemoglobin concentration can lead to increased oxygen delivery to tissues, helping to maintain tissue perfusion and prevent tissue hypoxia.

**Correct Answer:** . 170 ml