**Core Concept**
Ion exchange chromatography is a type of chromatography that separates molecules based on their ionic interactions with a stationary phase. This technique utilizes the principle of electrostatic attraction between oppositely charged ions to separate and purify molecules.

**Why the Correct Answer is Right**
In ion exchange chromatography, the stationary phase is typically a resin that is either positively or negatively charged. When a negatively charged molecule binds to the positively charged stationary phase, it can be selectively released into the mobile phase when a positively charged ion is introduced. This allows for the separation of negatively charged molecules from the stationary phase. The negatively charged molecules are attracted to the positively charged ions in the mobile phase, causing them to be eluted from the column.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the principle of ion exchange chromatography. Ion exchange chromatography relies on the interaction between oppositely charged ions, not the interaction between molecules with the same charge.
* **Option B:** This option is incorrect because it does not specifically describe the release of negatively charged molecules from the stationary phase. While it may be a general description of chromatography, it is not specific to the principle of ion exchange chromatography.
* **Option C:** This option is incorrect because it does not accurately describe the principle of ion exchange chromatography. Ion exchange chromatography relies on the interaction between oppositely charged ions, not the interaction between molecules with the same charge.

**Clinical Pearl / High-Yield Fact**
Ion exchange chromatography is commonly used in biochemistry and molecular biology to separate and purify proteins and other molecules. It is particularly useful for separating molecules with similar properties, such as charge and size.

**Correct Answer: C. Ion exchange chromatography. Ion exchange chromatography is a type of chromatography that separates molecules based on their ionic interactions with a stationary phase.**