**Core Concept**
Moxidectin is a macrocyclic lactone anthelmintic used in the treatment of various parasitic infections. It works by inhibiting the invertebrate glutamate-gated chloride channels, leading to paralysis and death of the parasites.

**Why the Correct Answer is Right**
Moxidectin was recently approved by the FDA for the treatment of onchocerciasis, a disease caused by the parasitic worm Onchocerca volvulus. This approval is significant as it provides a new treatment option for this debilitating disease, which can cause severe skin and eye lesions. Moxidectin's mechanism of action involves binding to the glutamate-gated chloride channels in the parasite's nervous system, leading to hyperpolarization and paralysis of the parasite.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as moxidectin is not primarily used for the treatment of strongyloidiasis, although it may have some efficacy against this parasite.
* **Option B:** This option is incorrect as moxidectin is not used for the treatment of hookworm infections, which are typically treated with other anthelmintics like albendazole or mebendazole.
* **Option C:** This option is incorrect as moxidectin is not used for the treatment of filariasis, which is typically treated with diethylcarbamazine or albendazole.

**Clinical Pearl / High-Yield Fact**
Moxidectin's approval for onchocerciasis treatment is a significant development in the field of parasitology, and it is essential for clinicians to be aware of its efficacy and potential side effects when treating patients with this disease.

**Correct Answer:** C.