## Core Concept
Psammoma bodies are a type of **calcification** found in certain types of tumors. They are small, round, laminated calcifications that can be seen under microscopic examination. Psammoma bodies are often associated with specific neoplastic and inflammatory conditions.

## Why the Correct Answer is Right
Psammoma bodies are characteristically found in **papillary thyroid carcinoma**. This type of thyroid cancer is known for its unique histological features, including the presence of psammoma bodies, which are a key diagnostic criterion. The formation of psammoma bodies is thought to result from the calcification of degenerating cells within the tumor.

## Why Each Wrong Option is Incorrect
* **Option A:** While certain types of **brain tumors** (such as meningiomas) can exhibit calcifications, psammoma bodies are not typically described in these contexts.
* **Option B:** **Serous cystadenocarcinoma** of the ovary can have psammoma bodies but they are more characteristically associated with papillary thyroid carcinoma.
* **Option C:** This option might be tempting, but it's not the best answer.
* **Option D:** This option is incorrect as it might refer to another condition not characteristically associated with psammoma bodies.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that the presence of psammoma bodies in a thyroid fine-needle aspiration biopsy is highly suggestive of **papillary thyroid carcinoma**. This histological feature can aid in the diagnosis and management of thyroid nodules.

## Correct Answer Line
**Correct Answer: C. Papillary thyroid carcinoma.**