**Core Concept**
Corticosteroids have been associated with the development of posterior subcapsular cataracts (PSC) due to their effect on the lens epithelial cells and the anterior lens capsule. This is a well-documented side effect of long-term corticosteroid use.

**Why the Correct Answer is Right**
The exact mechanism of corticosteroid-induced cataract formation is not fully understood, but it is believed to involve the inhibition of the enzyme aldose reductase, which is involved in the reduction of glucose to sorbitol in the lens epithelial cells. This leads to an accumulation of sorbitol, causing osmotic stress and subsequent damage to the lens fibers. Corticosteroids may also alter the expression of certain genes involved in lens cell growth and differentiation.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because posterior subcapsular cataracts (PSC) are not the only type of cataract associated with corticosteroid use. However, they are the most common type.
* **Option B:** This option is incorrect because corticosteroids do not typically cause cortical cataracts. Cortical cataracts are more often associated with aging and trauma.
* **Option C:** This option is incorrect because posterior polar cataracts are a rare congenital anomaly and are not typically associated with corticosteroid use.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that corticosteroid-induced cataracts are more likely to occur with prolonged use of high-dose corticosteroids, particularly in patients with a history of ocular surgery or trauma. Regular eye exams are crucial for patients on long-term corticosteroid therapy.

**Correct Answer: A. Posterior subcapsular cataract.**