**Core Concept**
The optic pathway is a complex neural circuit responsible for transmitting visual information from the retina to the brain. The pathway involves multiple neurons that process and relay visual signals, ultimately resulting in visual perception.

**Why the Correct Answer is Right**
The first-order neurons in the optic pathway are the retinal ganglion cells, which transmit visual signals from the retina to the optic nerve. The second-order neurons are the lateral geniculate nucleus (LGN) neurons, which receive input from the optic nerve and relay visual information to the primary visual cortex. This process involves a complex network of neurons and synapses that enable the processing of visual information.

**Why Each Wrong Option is Incorrect**
**Option A:** The optic nerve is not a second-order neuron, but rather the collection of axons from the retinal ganglion cells that transmit visual signals from the retina to the brain. It is the first-order neuron in the optic pathway.
**Option B:** The optic tract is a bundle of axons that carry visual information from the optic chiasm to the lateral geniculate nucleus, but it is not a second-order neuron itself.
**Option C:** The primary visual cortex is the final destination of the visual pathway, where visual information is processed and perceived. However, it is not a second-order neuron, but rather a higher-order processing center.

**Clinical Pearl / High-Yield Fact**
The optic pathway is a critical neural circuit that can be affected by various conditions, including optic neuritis, optic atrophy, and visual pathway gliomas. Understanding the anatomy and physiology of the optic pathway is essential for diagnosing and managing visual disorders.

**Correct Answer: C. Lateral geniculate nucleus (LGN) neurons.**