## Core Concept
Cold working is a metalworking process where a metal is shaped below its recrystallization temperature, resulting in strain hardening and residual stresses. Stress relief in cold working is crucial to prevent distortion or cracking.

## Why the Correct Answer is Right
The correct answer, . Annealing is a heat treatment process that involves heating the metal to a specific temperature and then cooling it. This process can relieve internal stresses, including those induced by cold working, by allowing the metal's microstructure to relax and reorganize.

## Why Each Wrong Option is Incorrect
* **Option A:** Quenching is a rapid cooling process used to achieve a specific microstructure, often to increase hardness. However, quenching can actually introduce more stresses rather than relieve them.
* **Option B:** Normalizing involves heating the metal to a specific temperature and then cooling it in air. While normalizing can relieve some stresses and refine the grain structure, it is not as effective for stress relief as annealing.
* **Option D:** Tempering is a heat treatment process used to reduce some of the hardness and increase toughness in quenched steels. It is not primarily used for stress relief.

## Clinical Pearl / High-Yield Fact
In the context of materials science and engineering, understanding the effects of different heat treatment processes on metals is crucial. A key point to remember is that **annealing** is specifically used for stress relief and can be critical in preventing material failure in engineering applications.

## Correct Answer Line
**Correct Answer: C. Annealing.**