**Core Concept**
Chloroquine toxicity is a well-documented adverse effect of long-term or high-dose use of this antimalarial medication. It primarily affects the visual and auditory systems, as well as the cardiovascular and neurological systems.

**Why the Correct Answer is Right**
Chloroquine toxicity is characterized by the accumulation of chloroquine in the retinal pigment epithelium, leading to photoreceptor damage and subsequent visual disturbances. The primary manifestations include maculopathy, characterized by a "bull's eye" maculopathy, and retinal pigment epithelium changes. Additionally, chloroquine toxicity can cause cardiomyopathy, conduction abnormalities, and neurological symptoms such as psychosis, seizures, and tremors.

**Why Each Wrong Option is Incorrect**
* **Option A:** Chloroquine toxicity is associated with a range of systemic symptoms, including gastrointestinal disturbances, but this is not a specific or unique manifestation.
* **Option B:** While chloroquine can cause cardiomyopathy, this is a recognized complication, not an "abnormality not commonly seen."
* **Option C:** This option is not provided.

**Clinical Pearl / High-Yield Fact**
A key aspect of chloroquine toxicity is the delayed onset of symptoms, which can occur months to years after initial exposure. This delayed presentation can make it challenging to diagnose and may lead to irreversible visual and neurological damage.

**Correct Answer: A. Chloroquine toxicity primarily affects the visual and auditory systems, as well as the cardiovascular and neurological systems, but gastrointestinal disturbances are not a unique or specific manifestation.