**Core Concept**
Chloroquine is a 4-aminoquinoline antimalarial drug that acts by inhibiting the parasite's heme detoxification pathway. It accumulates within the acidic lysosomes of the parasite, where it interferes with the digestion of heme, ultimately leading to parasite death. Chloroquine also has immunomodulatory effects and is used in the treatment of certain autoimmune diseases.

**Why the Correct Answer is Right**
Chloroquine's mechanism of action involves the inhibition of heme detoxification in the parasite, which is mediated by the enzyme heme glutathione S-transferase (HGST). By inhibiting this enzyme, chloroquine prevents the breakdown of heme, leading to the accumulation of toxic heme within the parasite. This results in the disruption of the parasite's metabolism and ultimately leads to its death. Chloroquine is also used in the treatment of autoimmune diseases such as rheumatoid arthritis and lupus due to its ability to modulate the immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** Chloroquine is not used in the treatment of hypertension. While it has some vasodilatory effects, this is not its primary use.
**Option B:** Chloroquine is not used in the treatment of bacterial infections. Its mechanism of action is specific to the malaria parasite and has no effect on bacteria.
**Option C:** Chloroquine is not used in the treatment of viral infections. Although it has some antiviral properties, this is not its primary use.

**Clinical Pearl / High-Yield Fact**
Chloroquine can cause retinal toxicity, particularly with long-term use or high doses. It is essential to monitor patients for signs of retinal damage, such as visual disturbances or changes in vision.

**Correct Answer:** D.