## Core Concept
The question pertains to the dental bleaching techniques, specifically focusing on home-applied bleaching methods. Dental bleaching, or teeth whitening, is a common cosmetic dental procedure used to lighten the color of teeth. Home-applied bleaching techniques involve the use of bleaching agents in a controlled manner by the patient at home.

## Why the Correct Answer is Right
The correct answer, **C. Carbamide peroxide**, is right because carbamide peroxide is a commonly used agent in home bleaching kits. It breaks down into hydrogen peroxide and urea, providing a sustained release of the bleaching agent. This property makes it suitable for at-home use, as it can be applied over a period (usually through custom-fitted trays) without causing significant tooth sensitivity or requiring professional supervision.

## Why Each Wrong Option is Incorrect
- **Option A:** Hydrogen peroxide is indeed a bleaching agent but is more commonly associated with in-office bleaching procedures due to its higher concentration and potential for causing tooth sensitivity. It's less suitable for home use without professional supervision.
- **Option B:** Sodium perborate is used in some dental bleaching procedures, particularly in non-vital tooth bleaching, but it's not the preferred agent for home-applied bleaching techniques.
- **Option D:** Potassium persulfate is not typically used as a primary bleaching agent in dental procedures.

## Clinical Pearl / High-Yield Fact
A key point to remember is that carbamide peroxide is often used in concentrations ranging from 10% to 22% for at-home bleaching, and it's essential for patients to follow the dentist's instructions carefully to avoid overuse and potential side effects like tooth sensitivity.

## Correct Answer: C. Carbamide peroxide