**Core Concept**
The question is testing the knowledge of the mechanism of epilation, which is the process of hair removal. In this context, an agent of epilation refers to a substance or method used to remove hair from the body.

**Why the Correct Answer is Right**
The correct answer is a chemical substance that works by dissolving the protein keratin, which is a key component of hair. This process is known as proteolysis. The specific enzyme responsible for breaking down keratin is trypsin, but the agent of epilation in question is a chemical that mimics this action. The chemical bonds in keratin are disrupted, leading to the disintegration of the hair shaft.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not involve the breakdown of keratin or the disruption of protein bonds.
* **Option B:** This option is incorrect because it refers to a method of hair removal that involves the use of heat, rather than a chemical substance.
* **Option C:** This option is incorrect because it refers to a substance that is used to reduce body hair, but not necessarily to remove it.

**Clinical Pearl / High-Yield Fact**
When using agents of epilation, it's essential to note that the concentration and duration of application can significantly impact the effectiveness and safety of the treatment. A common mistake is to leave the agent on for too long, which can lead to skin irritation and other complications.

**Correct Answer: D. Sodium Thioglycollate**