**Core Concept**
Ovarian tumors diagnosed during pregnancy pose a significant challenge in terms of management due to the risk of malignancy, potential effects on the fetus, and the need to balance maternal and fetal well-being. The primary concern is to differentiate between benign and malignant tumors, as this influences the treatment approach.

**Why the Correct Answer is Right**
The management of ovarian tumors during pregnancy involves a multidisciplinary approach, including obstetricians, gynecologic oncologists, and radiologists. The primary goal is to delay surgery until after the first trimester, if possible, to minimize the risk of miscarriage. If the tumor is malignant, the treatment of choice is surgical staging, which includes a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and lymph node dissection. This approach helps to determine the extent of the disease and guide further treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because delaying surgery until after the second trimester may not be feasible and may compromise the treatment outcome.

**Option B:** This option is incorrect because a simple oophorectomy is not sufficient for malignant ovarian tumors, and a more extensive surgical staging is required.

**Option C:** This option is incorrect because chemotherapy during pregnancy is generally avoided due to the potential risks to the fetus, unless the maternal life is at risk.

**Clinical Pearl / High-Yield Fact**
In cases of ovarian tumors diagnosed during pregnancy, it's essential to establish a multidisciplinary team to manage the patient, and a thorough discussion with the patient about the risks and benefits of each treatment option is crucial.

**Correct Answer:** C. Surgical staging with total abdominal hysterectomy, bilateral salpingo-oophorectomy, and lymph node dissection.