**Core Concept:**
Malignant ovarian tumors, also known as ovarian carcinomas, are a group of cancerous tumors that can form in the ovaries. The primary treatment options for malignant ovarian tumors aim to eradicate the cancer cells, control symptoms, and improve the survival rate.

**Why the Correct Answer is Right:**
The correct answer is **D. Surgery and Chemotherapy**. Surgery plays a crucial role in the treatment of malignant ovarian tumors as it allows for the complete removal of the tumor, reducing the tumor burden and preventing further growth and spread of cancer cells. Chemotherapy is also essential, as it involves using drugs to kill cancer cells that are not removable through surgery. Chemotherapy is usually administered after surgery to kill any remaining cancer cells and prevent relapse.

**Why Each Wrong Option is Incorrect:**
A. **Radiation therapy (A)**: While radiation therapy is used in some cases for ovarian cancer treatment, surgery and chemotherapy are generally considered more effective for malignant ovarian tumors.
B. **Observation and hormone therapy (B)**: Malignant ovarian tumors often require more aggressive treatment options, such as surgery and chemotherapy, to control the cancer and improve outcomes.
C. **Endoscopic surgery (C)**: While endoscopic surgery (laparoscopy) is a minimally invasive approach, it may not be as effective as open surgery in removing malignant ovarian tumors, especially if they are large or have spread beyond the ovaries.

**Clinical Pearl / High-Yield Fact:**

Given the importance of early detection and intervention, **mass screening programs** for ovarian cancer are being explored to improve outcomes. However, due to the often asymptomatic nature of early-stage ovarian cancer, the effectiveness of these programs is still uncertain. Early detection through regular screening tests like CA-125 levels and transvaginal ultrasound may improve the chances of successful treatment.

In conclusion, surgery and chemotherapy are the primary treatments for malignant ovarian tumors, while radiation therapy, observation, and endoscopic surgery are usually not as effective. Mass screening programs are being studied as a potential method to detect ovarian cancer early and improve treatment outcomes. It is essential for medical students and healthcare professionals to be aware of the available treatment options and their limitations to provide accurate and appropriate care for patients with ovarian cancer.