**Core Concept**
The question pertains to the effects of radiation on the eye, specifically the development of cataracts following radiation-induced injury. **Radiation cataracts** are a type of **ionizing radiation** injury that can lead to opacification of the lens in the eye.

**Why the Correct Answer is Right**
Given the context, it's known that radiation-induced cataracts typically affect the **posterior subcapsular** region of the lens. This area is particularly susceptible due to the high mitotic activity of the **epithelial cells** in this region, making it more vulnerable to radiation damage.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it doesn't specify the correct region of the lens affected by radiation.
**Option B:** Similarly, this option is wrong as it doesn't accurately describe the location of radiation-induced cataract formation.
**Option C:** This choice is incorrect because, while it might relate to cataract formation, it doesn't specifically address radiation-induced injury.
**Option D:** This option is also incorrect as it doesn't correctly identify the part of the lens affected by radiation.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that radiation exposure can lead to cataract formation, particularly in the **posterior subcapsular** region of the lens, due to its high sensitivity to ionizing radiation. This knowledge is vital for managing patients who have undergone radiation therapy.

**Correct Answer:** Correct Answer: D. Posterior subcapsular.