**Core Concept**
The patient's presentation is consistent with a Bartholin's gland cyst, which is a benign, fluctuant swelling at the introitus, often resulting from obstruction of the gland's duct. Bartholin's glands are two small exocrine glands located on either side of the vaginal opening, secreting mucus to lubricate the vagina.

**Why the Correct Answer is Right**
The treatment of choice for a Bartholin's gland cyst is surgical excision of the gland, often performed under local anesthesia. This procedure, known as a Bartholin's gland cyst marsupialization, involves making an incision in the cyst and creating a new duct to allow the gland to drain. This procedure can be done in the office or in an outpatient surgical setting. The goal is to prevent recurrent cyst formation.

**Why Each Wrong Option is Incorrect**
**Option A:** Antibiotics are often prescribed to prevent infection, but they do not treat the underlying cyst. Antibiotics are not the primary treatment for a Bartholin's gland cyst.
**Option B:** Warm compresses may help to reduce the size of the cyst, but they do not treat the underlying obstruction. Warm compresses are a conservative approach, but they are not the best treatment for a Bartholin's gland cyst.
**Option C:** Hormonal therapy is not typically used to treat Bartholin's gland cysts. Hormonal therapy may be used to treat other conditions, but it is not the best treatment for a Bartholin's gland cyst.

**Clinical Pearl / High-Yield Fact**
A Bartholin's gland cyst can be distinguished from a Bartholin's gland abscess by its fluctuant, non-tender nature. A Bartholin's gland abscess is a painful, tender mass that requires incision and drainage.

**Correct Answer: D. Surgical excision of the Bartholin's gland.**