**Core Concept**
Gene amplification is a process by which a specific gene or DNA sequence is copied multiple times in a cell's genome, often leading to an increase in the production of a particular protein. This phenomenon is commonly observed in cancer cells, where it can contribute to the development and progression of the disease.

**Why the Correct Answer is Right**
Gene amplification is primarily achieved through the process of **replication**, where the cell's DNA is duplicated, and the amplified gene is selectively replicated multiple times. This can occur through various mechanisms, including errors during DNA replication, recombination, and the activity of enzymes such as **DNA polymerase**. Gene amplification can also be facilitated by the presence of **oncogenes**, which are genes that have the potential to become cancer-causing when overexpressed.

**Why Each Wrong Option is Incorrect**
**Option A:** This option does not specify a mechanism for gene amplification. While it might be related to gene expression, it does not directly answer the question.
**Option B:** This option is not a recognized mechanism for gene amplification. While it might be related to gene regulation, it is not directly relevant to the process of amplifying a gene.
**Option C:** This option does not accurately describe a mechanism for gene amplification. While it might be related to DNA repair, it is not directly relevant to the process of amplifying a gene.

**Clinical Pearl / High-Yield Fact**
Gene amplification is a common feature of cancer cells, where it can contribute to the development and progression of the disease. It is often associated with the amplification of oncogenes, which can lead to uncontrolled cell growth and tumor formation.

**Correct Answer: C. Replication**