**Core Concept**
Endodermal sinus tumor (EST), also known as yolk sac tumor, is a malignant germ cell tumor that primarily affects the gonads but can also occur in extragonadal sites. It is characterized by the presence of a specific histological pattern and the production of certain tumor markers.

**Why the Correct Answer is Right**
The correct answer is related to the presence of Schiller-Duval bodies, which are a hallmark of endodermal sinus tumors. These structures consist of a central blood vessel surrounded by a rosette of cuboidal cells, resembling a glomerulus. The tumor cells produce alpha-fetoprotein (AFP), a tumor marker that is often elevated in patients with EST.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might refer to the presence of Reinke crystals, which are characteristic of Leydig cell tumors, not endodermal sinus tumors.
**Option B:** This option might refer to the presence of Call-Exner bodies, which are characteristic of granulosa cell tumors, not endodermal sinus tumors.
**Option C:** This option might refer to the presence of psammoma bodies, which are characteristic of papillary thyroid carcinoma, not endodermal sinus tumors.

**Clinical Pearl / High-Yield Fact**
Endodermal sinus tumors are highly sensitive to chemotherapy and radiation, making them a treatable malignancy. However, they can recur and metastasize, emphasizing the need for close follow-up and prompt intervention.

**Correct Answer:** D.