**Core Concept**
The patient's presentation suggests a possible ovarian tumor, likely a malignancy, given the complex nature of the mass and the elevated CA-125 levels. The clinical findings, including the nodular, tender uterosacral ligament and the retroverted uterus, may indicate ovarian torsion or endometriosis.

**Why the Correct Answer is Right**
The initial step in managing a suspected ovarian tumor, especially when it's complex and associated with elevated CA-125 levels, is to rule out malignancy. A laparoscopic evaluation or surgical staging is essential to assess the tumor's nature and extent. This approach allows for both diagnostic confirmation and potential debulking of the tumor, if necessary. The correct answer involves a surgical intervention that enables a thorough examination of the pelvic organs and the collection of tissue samples for histopathological examination.

**Why Each Wrong Option is Incorrect**
**Option A:** A CT scan or MRI may provide additional information about the tumor's extent and potential spread but would not be the initial next step in management. These imaging modalities are useful for further evaluation but do not replace the need for a thorough surgical assessment.

**Option B:** Hormonal evaluation and management are not the primary concern in this scenario. While hormonal imbalances may be associated with ovarian tumors, addressing them would not address the underlying issue of the suspected malignancy.

**Option C:** Chemotherapy or radiation therapy may be part of the treatment plan for ovarian cancer but would not be the initial next step in management. These modalities are typically reserved for after a definitive diagnosis and potentially after surgical debulking.

**Option D:** A trial of antibiotics or anti-inflammatory medications may be warranted if there's suspicion of infection or inflammation but would not address the underlying concern of a possible ovarian malignancy.

**Clinical Pearl / High-Yield Fact**
The CA-125 level is often elevated in women with ovarian cancer, but it's essential to note that this marker is not specific for ovarian cancer and can be elevated in other conditions, such as endometriosis or pelvic inflammatory disease. A high CA-125 level, in conjunction with clinical findings, can raise the suspicion of ovarian cancer and prompt further evaluation.

**Correct Answer:** C. Laparoscopic surgical staging is the initial next step in management.