**Core Concept**
Dysgerminoma is a type of **germ cell tumor** that occurs in the ovaries, and its treatment depends on the stage at which it is diagnosed. In stage 1A, the cancer is limited to one ovary, and there is no ascites or tumor on the external surface of the ovary.

**Why the Correct Answer is Right**
The treatment of choice for stage 1A dysgerminoma is typically **surgical removal of the affected ovary**, as the cancer is localized and has not spread to other parts of the body. This approach helps preserve fertility in young patients.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not specified.
**Option B:** Incorrect because it is not specified.
**Option C:** Incorrect because it is not specified.
**Option D:** Incorrect because it is not specified, but in general, more aggressive treatments are reserved for more advanced stages.

**Clinical Pearl / High-Yield Fact**
In dysgerminoma, **fertility-sparing surgery** is often the preferred treatment for early-stage disease, especially in young women who wish to preserve their reproductive capabilities.

**Correct Answer:** Not provided in the query, however, typically for stage 1A dysgerminoma, the correct answer would involve a conservative surgical approach.