**Core Concept**
The management of ovarian cancer involves monitoring and surveillance for recurrence, with CA 125 being a tumor marker used to detect rising levels indicative of disease progression. The rising level of CA 125 in a patient with a history of ovarian cancer suggests possible recurrence.

**Why the Correct Answer is Right**
The next step in managing a patient with rising CA 125 levels and a history of ovarian cancer is to perform a thorough imaging study, such as a CT scan of the abdomen and pelvis. This is because the rising CA 125 level may indicate recurrence of the ovarian cancer, and imaging studies can help identify the location and extent of the disease. The CT scan can also evaluate for any potential metastatic disease to the liver or other organs.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a simple ultrasound may not provide sufficient information to evaluate for recurrence or metastatic disease, and may not be as sensitive as a CT scan.
* **Option B:** This option is incorrect because a liver function test (LFT) is not a diagnostic tool to evaluate for ovarian cancer recurrence, and would not provide information on the location or extent of the disease.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that a rising CA 125 level in a patient with a history of ovarian cancer requires prompt investigation with imaging studies to evaluate for recurrence or metastatic disease.

**Correct Answer:** C. CT scan of the abdomen and pelvis.