**Core Concept**
Toxoplasmosis is a protozoal infection caused by Toxoplasma gondii, which can lead to ocular inflammation in immunocompromised patients, including those with AIDS. This occurs due to the reactivation of latent Toxoplasma gondii infection in the brain and eyes.

**Why the Correct Answer is Right**
Toxoplasmosis is the most common opportunistic infection causing ocular inflammation in AIDS patients. This is because Toxoplasma gondii has a predilection for the retina and choroid in the eye, leading to lesions that can cause vision loss. The infection occurs due to the reactivation of latent Toxoplasma gondii in the brain and eyes, which is facilitated by the compromised immune system of the patient.

**Why Each Wrong Option is Incorrect**
* **Option A:** Histoplasmosis is another opportunistic infection that can cause ocular inflammation, but it is less common than toxoplasmosis in AIDS patients.
* **Option B:** Cytomegalovirus (CMV) retinitis is a common opportunistic infection in AIDS patients, but it typically presents as a retinal necrosis rather than ocular inflammation.
* **Option D:** Cryptococcosis is an opportunistic fungal infection that can cause ocular inflammation, but it is less common than toxoplasmosis in AIDS patients.

**Clinical Pearl / High-Yield Fact**
Toxoplasmosis is often asymptomatic in immunocompetent individuals but can cause severe ocular inflammation in immunocompromised patients, highlighting the importance of serological screening for Toxoplasma gondii in patients with AIDS.

**Correct Answer:** C. Toxoplasma gondii