**Core Concept**
Synovial sarcoma is a type of malignant tumor that arises near the joints of the arm, neck, or leg. It is characterized by a specific genetic translocation that involves the SS18 gene, leading to the formation of a fusion protein that drives tumor growth.

**Why the Correct Answer is Right**
The correct translocation in synovial sarcoma is t(X;18)(p11.2;q11.2), which involves the fusion of the SS18 gene on chromosome 18 with one of several genes on the X chromosome, including SSX1, SSX2, or SSX4. This translocation leads to the formation of a chimeric protein that disrupts normal cellular function and promotes tumorigenesis. The SS18-SSX fusion protein has been shown to have oncogenic properties, including the ability to transform cells and promote tumor growth.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the correct chromosomes involved in the translocation.
* **Option B:** This option is incorrect because it does not identify the SS18 gene as the gene involved in the translocation.
* **Option C:** This option is incorrect because it does not specify the correct X chromosome gene involved in the translocation.

**Clinical Pearl / High-Yield Fact**
Synovial sarcoma is a rare but aggressive tumor that often presents with a poor prognosis if left untreated. Early diagnosis and treatment are critical to improve patient outcomes.

**Correct Answer: C. t(X;18)(p11.2;q11.2)**