**Core Concept**
Endodermal sinus tumors (ESTs), also known as yolk sac tumors, are a type of germ cell tumor that primarily affects the gonads but can also occur in extragonadal sites. They are the most common malignant germ cell tumor in children and are characterized by the production of alpha-fetoprotein (AFP).

**Why the Correct Answer is Right**
Endodermal sinus tumors are known for their high metastatic potential and aggressive behavior. They contain Schiller-Duval bodies, which are characteristic histological structures consisting of a central blood vessel surrounded by embryonic mesenchyme and surrounded by embryonic epithelium. The production of AFP is a hallmark of ESTs and is used as a tumor marker for diagnosis and monitoring.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because ESTs do produce AFP.
**Option B:** Incorrect because ESTs are known for their aggressive behavior and high metastatic potential.
**Option C:** Incorrect because Schiller-Duval bodies are a characteristic histological feature of ESTs.

**Clinical Pearl / High-Yield Fact**
A classic exam trap is to remember that ESTs are often associated with elevated AFP levels, which can also be seen in other conditions such as hepatocellular carcinoma and certain infections. However, the context of the clinical presentation and imaging findings can help to narrow down the diagnosis.

**Correct Answer: None**