**Core Concept**
The aortic hiatus is an anatomical opening in the diaphragm that allows for the passage of vital structures between the thoracic and abdominal cavities. This hiatus is formed by the right and left crus of the diaphragm.

**Why the Correct Answer is Right**
The aortic hiatus transmits the thoracic duct, aortic arch, and the azygos vein. The thoracic duct is a crucial lymphatic vessel that drains lymph from the lower body and returns it to the bloodstream at the junction of the left jugular and left subclavian veins. The aortic arch is the part of the aorta that arises from the ascending aorta and gives off branches to supply the head and upper limbs. The azygos vein is a vital vessel that drains blood from the posterior walls of the thorax and abdomen into the superior vena cava.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not specified, so we cannot evaluate its correctness.
* **Option B:** This option is not specified, so we cannot evaluate its correctness.
* **Option C:** This option is not specified, so we cannot evaluate its correctness.
* **Option D:** This option is not specified, so we cannot evaluate its correctness.

**Clinical Pearl / High-Yield Fact**
The aortic hiatus is a critical anatomical landmark that can be relevant in surgical procedures involving the diaphragm, such as hernia repairs or thoracic surgeries. Understanding the structures that pass through this hiatus is essential for identifying potential complications or areas of concern during these procedures.

**Correct Answer: C. Thoracic duct, aortic arch, and the azygos vein.**