**Core Concept**
The question tests the student's ability to identify a specific type of ovarian tumor based on histopathological characteristics. Mucin-secreting cells with signet ring shapes are a distinctive feature of a particular tumor type.

**Why the Correct Answer is Right**
The presence of mucin-secreting cells with signet ring shapes is characteristic of Krukenberg tumors. These tumors typically arise from gastric adenocarcinoma that has metastasized to the ovaries. The signet ring cells are a result of the mucin accumulation within the cytoplasm of the tumor cells. This is a classic example of metastatic disease to the ovaries, rather than a primary ovarian tumor.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be a distractor for those who are not familiar with the specific histopathological features of Krukenberg tumors. However, it is not a correct diagnosis based on the provided information.
**Option B:** This option could be a distractor for those who are not considering the possibility of metastatic disease. However, the presence of mucin-secreting cells with signet ring shapes is not a characteristic feature of primary ovarian tumors.
**Option C:** This option might be a distractor for those who are not considering the specific histopathological features of Krukenberg tumors. However, it is not a correct diagnosis based on the provided information.

**Clinical Pearl / High-Yield Fact**
Krukenberg tumors are a classic example of metastatic disease to the ovaries. They are typically associated with gastric adenocarcinoma, and the presence of mucin-secreting cells with signet ring shapes is a distinctive feature of this tumor type.

**Correct Answer:** D. Krukenberg tumors are a type of metastatic ovarian tumor characterized by mucin-secreting cells with signet ring shapes.