## **Core Concept**
The question tests knowledge of ocular hypotensive agents, specifically their side effects in vulnerable populations like infants. Ocular hypotensive agents are used to reduce intraocular pressure (IOP) in conditions like glaucoma. The side effect of apnea in infants is particularly concerning and points towards a systemic effect of the drug.

## **Why the Correct Answer is Right**
The correct answer, **Propranolol**, is a non-selective beta-blocker used in the treatment of glaucoma to decrease intraocular pressure. Propranolol can cause bronchospasm and has effects on the central nervous system, but importantly, it can also cause apnea in infants. This is particularly concerning because infants have a higher risk of experiencing this side effect due to their immature respiratory control mechanisms. Propranolol crosses the blood-brain barrier and can affect the respiratory centers in the brainstem, potentially leading to apnea.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while it might represent another ocular hypotensive agent, without specifying, we can't directly assess its validity. However, given the context, it's less likely to be associated with apnea in infants compared to propranolol.
- **Option B:** Similarly, this option lacks specificity but could represent another class of drugs used in glaucoma treatment, such as prostaglandin analogs, carbonic anhydrase inhibitors, or alpha agonists, which have different side effect profiles.
- **Option D:** This option is also not specified but could represent a different drug class used for glaucoma treatment. Drugs in other classes have side effects but are less commonly associated with apnea in infants compared to propranolol.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **propranolol**, a non-selective beta-blocker, can cause apnea in infants. This is a critical consideration when treating glaucoma or using propranolol for other indications in this vulnerable population. Clinicians must weigh the benefits against the risks and consider alternative treatments when possible.

## **Correct Answer: C. Propranolol**