**Core Concept**
The **posterior mediastinum** is a compartment of the thoracic cavity that contains various structures, including the esophagus, thoracic aorta, and nerves. Tumors in this region can arise from these structures or from neurogenic tissues. The most common type of tumor in this area is related to neural tissue.

**Why the Correct Answer is Right**
The most common posterior mediastinal tumors are **neurogenic tumors**, which arise from nerve cells or nerve sheaths. These tumors can be benign or malignant and include types such as neurofibromas, schwannomas, and neuroblastomas. They are more common in the posterior mediastinum due to the presence of neural tissue in this compartment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a tumor type commonly found in the posterior mediastinum.
**Option B:** This option is incorrect as it is not the most common type of tumor in the posterior mediastinum.
**Option C:** This option is incorrect because, although neurogenic tumors are common, the specific type mentioned here is not the most frequent.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that **neurogenic tumors** are the most common tumors of the posterior mediastinum, especially in children and young adults.

**Correct Answer:** D. Neurogenic tumor.