**Core Concept**
The patient's presentation of night blindness, tubular vision, and characteristic fundus examination findings suggests a specific retinal dystrophy characterized by progressive rod photoreceptor degeneration. This condition is a classic example of a hereditary retinal disorder.

**Why the Correct Answer is Right**
The patient's symptoms and examination findings are consistent with Retinitis Pigmentosa (RP), a group of genetic disorders affecting the retina's rod photoreceptors. The characteristic bony corpuscles or spicules of pigmentation in the midperipheral retina, waxy pallor of the disc, attenuation of arterioles, and ring scotoma on perimetry are hallmarks of RP. The subnormal electroretinogram (ERG) further supports this diagnosis, as RP is characterized by reduced rod function.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely incorrect because RP primarily affects the rod photoreceptors, leading to night blindness and peripheral visual field loss. Cone photoreceptor disorders, such as cone-rod dystrophy, would present differently.

**Option B:** This option is incorrect because RP is a hereditary disorder, and while age-related macular degeneration (AMD) can cause visual impairment, it does not typically present with the characteristic fundus findings seen in RP.

**Option C:** This option is incorrect because RP is a retinal disorder, and while glaucoma can cause visual field loss, it does not typically present with the characteristic bony corpuscles or spicules of pigmentation in the midperipheral retina.

**Option D:** This option is incorrect because RP is a hereditary disorder, and while Leber's congenital amaurosis is a severe form of RP, it typically presents in infancy or early childhood, whereas this patient is described as a young man.

**Clinical Pearl / High-Yield Fact**
Retinitis Pigmentosa is a classic example of a hereditary retinal disorder, and a careful fundus examination is essential in making the diagnosis. The characteristic bony corpuscles or spicules of pigmentation in the midperipheral retina are a key finding in RP.

**Correct Answer:** C. **Retinitis Pigmentosa**