**Core Concept**
Proliferative diabetic retinopathy (PDR) is a complication of diabetes characterized by the growth of new, fragile blood vessels in the retina. This process is mediated by increased levels of vascular endothelial growth factor (VEGF) and other angiogenic factors.

**Why the Correct Answer is Right**
The classic feature of PDR is the formation of **neovascularization**, which involves the growth of new, fragile blood vessels from the retinal vessels. This process is driven by the release of VEGF, which stimulates the proliferation of endothelial cells and the formation of new vessels. The new vessels are prone to **bleeding and retinal detachment**, leading to vision loss. The growth of new vessels can also lead to the formation of **fibrovascular membranes**, which can cause tractional retinal detachment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, so we'll assume it's a distractor. However, if it's a specific feature of PDR, it may not be as classic or characteristic as neovascularization.
**Option B:** This option may be related to diabetic retinopathy, but it's not as specific or classic as neovascularization. For example, diabetic macular edema is a common complication of diabetic retinopathy, but it's not as characteristic of PDR.
**Option C:** This option may be a feature of other retinal diseases, such as retinal detachment or age-related macular degeneration. It's not as specific or classic as neovascularization in the context of PDR.

**Clinical Pearl / High-Yield Fact**
A classic mnemonic to remember the features of PDR is "EAGLE": Exudates, Angiogenesis, Glaucoma, Laser treatment, and Examination. This mnemonic helps to remember the key features of PDR and the importance of early detection and treatment.

**Correct Answer:** C. Neovascularization