**Core Concept**
The question is testing the student's knowledge of ovarian tumors and their potential for metastasis. Ovarian tumors can be benign or malignant, and their behavior varies depending on the **histological type**. The **spread of ovarian cancer** can occur through direct invasion, lymphatic spread, or hematogenous spread.

**Why the Correct Answer is Right**
The correct answer is related to the type of ovarian tumor that has a high propensity for **bilateral involvement**, which is a characteristic feature of certain malignant ovarian tumors. Specifically, **serous cystadenocarcinoma** is known for its tendency to spread to the opposite ovary, either by direct extension or through metastasis. This is due to the **transcoelomic spread** of tumor cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Is incorrect because it does not specify a tumor type known for bilateral involvement.
**Option B:** Is incorrect as it refers to a benign tumor type.
**Option C:** Is incorrect because, although it can be malignant, it is not as commonly associated with bilateral ovarian involvement as the correct answer.

**Why Each Wrong Option is Incorrect (continued)**
**Option D:** Is incorrect as it is not typically associated with ovarian metastasis to the opposite ovary.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **serous cystadenocarcinoma** is the most common type of malignant ovarian tumor and has a high propensity for **bilateral involvement**. This is crucial for clinical management and surgical planning.

**Correct Answer:** D. Serous cystadenocarcinoma.