**Core Concept**
Pre-senile cataract refers to a type of cataract that occurs in individuals under the age of 60, often due to metabolic or systemic disorders. These cataracts can be caused by various factors, including diabetes, trauma, and certain medications.

**Why the Correct Answer is Right**
One of the key causes of pre-senile cataract is diabetes mellitus, which leads to the accumulation of sorbitol in the lens fibers due to the enzyme aldose reductase. This accumulation of sorbitol causes osmotic changes, leading to water influx and swelling of the lens fibers, resulting in cataract formation. Another cause is trauma, which can lead to cataract formation due to the release of inflammatory mediators and oxidative stress.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is not a recognized cause of pre-senile cataract. **Option B:** This option is incorrect as it is a well-known cause of pre-senile cataract. **Option C:** This option is incorrect as it is not a primary cause of pre-senile cataract, although it may contribute to cataract formation in certain cases.

**Clinical Pearl / High-Yield Fact**
It is essential to note that pre-senile cataracts can be reversible with treatment of the underlying cause, such as diabetes or trauma. Early diagnosis and management are crucial to prevent further vision loss.

**Correct Answer:** B. Diabetes mellitus is a well-recognized cause of pre-senile cataract, while the other options are not primary causes of this condition.