## **Core Concept**
The question pertains to a case of a patient developing a red eye two days after an episode of malaria. This scenario suggests a complication or secondary condition related to malaria or its treatment. Malaria, caused by Plasmodium parasites and transmitted by Anopheles mosquitoes, can lead to various complications, including ocular manifestations.

## **Why the Correct Answer is Right**
The correct answer, **D.**, implies that the probable cause of the red eye in this context could be related to the treatment or complications of malaria. One well-known ocular side effect associated with certain antimalarial drugs, particularly chloroquine and hydroxychloroquine, is retinal toxicity. However, these drugs are less commonly used now due to resistance. Another possibility is the development of a condition like subconjunctival hemorrhage, which can occur due to the severity of the malaria infection or its treatment. Given the acute presentation, an allergic reaction or a secondary infection could also be considered.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Without specifying what A is, we cannot directly address its incorrectness. However, if A suggests a direct complication of malaria like cerebral malaria or severe anemia, these are less likely to present as a red eye directly.
- **Option B:** Similarly, without the content of B, we can't directly refute it. If B proposes a common cause of red eye like conjunctivitis, it might not be directly linked to malaria unless specified as a secondary infection.
- **Option C:** If C suggests another antimalarial drug side effect or a condition not directly related to malaria or its treatment, it would be incorrect based on the context provided.

## **Clinical Pearl / High-Yield Fact**
A memorable point for students is that malaria and its treatment can have ocular complications. Chloroquine, for instance, is known for its potential to cause retinal toxicity with long-term use. A high-yield fact is to consider drug side effects and complications in patients with a history of malaria, especially when they present with ocular symptoms.

## **Correct Answer:** **D.**