**Core Concept**
The orbit is a complex anatomical structure that houses the eyeball and its associated nerves, blood vessels, and muscles. It is bounded by several layers of fascia, including the orbital and bulbar fascia, and contains important nerves such as the abducent nerve. The superior ophthalmic veins are also found within the orbit, playing a crucial role in the venous drainage of the eye.

**Why the Correct Answer is Right**
The contents of the orbit include the eyeball, orbital fat, extraocular muscles (such as the levator palpebrae superioris and the rectus muscles), and the nerves and blood vessels that supply them. The orbital fascia is a key component of the orbit, providing a fibrous layer that separates the orbital contents from the surrounding tissues. The abducent nerve, responsible for controlling the lateral rectus muscle, is also a critical structure within the orbit. The superior ophthalmic veins drain the orbit and are a key part of the venous circulation of the eye.

**Why Each Wrong Option is Incorrect**
**Option A:** Orbital and bulbar fascia are indeed components of the orbit, but they are not the only contents. This option is incomplete, making it incorrect.

**Option B:** The abducent nerve is indeed a content of the orbit, but it is not the only one. This option is also incomplete, making it incorrect.

**Option C:** The superior ophthalmic veins are a content of the orbit, but they are not the only one. This option is also incomplete, making it incorrect.

**Clinical Pearl / High-Yield Fact**
When examining a patient with a suspected orbital fracture, it is essential to note that the orbit is a complex structure with multiple layers of fascia and a rich vascular supply. A thorough understanding of the orbital anatomy is crucial for accurate diagnosis and management.

✓ Correct Answer: D. All of the Above