**Core Concept**
The question is testing the knowledge of ovarian tumor behavior, specifically the likelihood of metastasis to the opposite ovary. This is a key concept in gynecologic oncology, as the spread of tumors to the opposite ovary can significantly impact treatment and prognosis.

**Why the Correct Answer is Right**
The correct answer is **serous cystadenocarcinoma**. Serous tumors are known to have a high propensity for peritoneal dissemination and metastasis, including involvement of the opposite ovary. This is due to the production of mucin, which can spread along the peritoneal surfaces, leading to widespread disease. Additionally, serous tumors often have a high-grade histology, which is associated with increased aggressiveness and a higher likelihood of metastasis.

**Why Each Wrong Option is Incorrect**
**Option A:** **Mucinous cystadenocarcinoma** is less likely to involve the opposite ovary by metastasis, as it tends to grow larger and more locally destructive, rather than spreading through the peritoneum.

**Option B:** **Dysgerminoma** is a type of germ cell tumor that is less likely to metastasize to the opposite ovary, as it tends to grow locally and is often confined to one ovary.

**Option C:** **Endometrioid adenocarcinoma** is a type of ovarian tumor that is more commonly associated with endometriosis, and is less likely to involve the opposite ovary by metastasis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that serous tumors have a higher propensity for peritoneal dissemination and metastasis, making them more likely to involve the opposite ovary. This is a key factor in the management and prognosis of ovarian cancer.

**Correct Answer:** C. Dysgerminoma