## Core Concept
The question tests knowledge on types of cataracts, specifically focusing on reversible causes. A cataract is a clouding of the lens in the eye that affects vision. Reversible cataracts are those that can potentially resolve or improve with medical management or removal of the underlying cause.

## Why the Correct Answer is Right
The correct answer, **C. Cortical cataract associated with diabetes (or more accurately, Cataract associated with systemic diseases like diabetes)**, relates to cataracts that can sometimes be managed or improved by controlling the underlying condition. For instance, in diabetes, rapid changes in blood glucose levels can cause fluctuations in the lens's water content, leading to swelling and the development of cataracts. Managing blood glucose levels can potentially halt the progression or even lead to some reversal of such cataracts.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not specify a type of cataract known to be reversible.
- **Option B:** This option is incorrect as it does not relate to a commonly recognized reversible cause of cataract.
- **Option D:** This option is incorrect because posterior subcapsular cataracts are not typically considered reversible; they often require surgical intervention.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **cataracts associated with systemic diseases** like diabetes can sometimes show improvement or stabilization with tight control of the underlying condition. However, not all cataracts are reversible, and many require surgical intervention.

## Correct Answer Line
**Correct Answer: C. Cortical cataract associated with diabetes.**