**Core Concept**
The question tests the understanding of the **pupillary light reflex** pathway, which involves the **optic nerve (CN II)** for afferent input and the **oculomotor nerve (CN III)** for efferent output. The reflex is crucial for regulating pupil size in response to light.

**Why the Correct Answer is Right**
Since the question mentions normal vision, the **optic nerve (CN II)**, responsible for transmitting visual information, is intact. The absence of both direct and consensual light reflexes indicates a problem with the efferent pathway of the pupillary light reflex, which is controlled by the **oculomotor nerve (CN III)**. This nerve's paralysis or dysfunction would lead to the described symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the optic nerve's primary role is vision, not the pupillary reflex.
**Option B:** Incorrect as the oculomotor nerve controls the reflex, not the trochlear nerve.
**Option D:** Incorrect because the abducens nerve is involved in eye movement, not the pupillary light reflex.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the **pupillary light reflex** involves both **CN II** (afferent) and **CN III** (efferent) pathways. Any disruption in these nerves can lead to abnormalities in pupil reaction.

**Correct Answer:** C. III