**Core Concept:** The retina is a part of the eye that detects light and converts it into electrical signals. It is composed of several layers, including the inner nuclear layer (INL), outer nuclear layer (ONL), ganglion cell layer (GCL), and photoreceptor layer (PRL). The optic nerve is responsible for transmitting visual information from the retina to the brain.

**Why the Correct Answer is Right:** The correct answer, **Option D: Optic Disc**, is the part of the retina that continues as the optic nerve. The optic disc, also known as the optic cup, is the location where the retinal layers merge, forming a single structure before entering the optic nerve head and continuing as the optic nerve.

**Why Each Wrong Option is Incorrect:**

A. **Inner Nuclear Layer (INL)**: The INL is a layer within the retina that contains bipolar cells, amacrine cells, and horizontal cells. It is not responsible for continuing as the optic nerve.

B. **Optic Nerve Head**: The optic nerve head is the point where the optic nerve exits the eye and connects to the brain. It is not the continuation of the retina.

C. **Ganglion Cell Layer (GCL)**: The GCL contains ganglion cells, which transmit visual information to the brain. It is not responsible for continuing as the optic nerve.

D. **Optic Disc**: As mentioned, the optic disc is where the retinal layers merge, forming the optic nerve. This option is correct.

**Clinical Pearl:** The optic disc plays a crucial role in the transmission of visual information from the eye to the brain, forming the basis for the visual pathway and ultimately enabling us to see. This structural connection between retina and optic nerve is essential for maintaining proper eye function and visual health.