Okay, let's tackle this question about the ovo-viviparous nematode. First, I need to recall what ovo-viviparity means. From what I remember, ovo-viviparous refers to organisms where the eggs develop inside the mother's body but are nourished through the egg yolk rather than from the mother's body. So the offspring hatch inside the mother and are then born alive. Now, nematodes are a phylum of roundworms, and I need to think about which species in this phylum exhibit this reproductive strategy.

I know that some parasitic nematodes have complex life cycles. For example, Dracunculus medinensis (Guinea worm) is a nematode, but I'm not sure about its reproductive method. Then there's Onchocerca volvulus, which causes river blindness. I think it's transmitted by blackflies and has microfilariae, but again, not sure about ovo-viviparity.

Wait, maybe it's Loa loa? No, Loa loa is transmitted by deerflies and causes loiasis. The microfilariae circulate in the blood. Another possibility is Wuchereria bancrofti, which causes lymphatic filariasis. These are all filarial worms, and I recall that they are ovo-viviparous. The female worms produce microfilariae that are released into the host's bloodstream. The microfilariae are then ingested by vectors like mosquitoes. So the development from egg to larva happens inside the mother worm, making them ovo-viviparous.

Let me check other options. Ascaris lumbricoides is not ovo-viviparous; it's oviparous, laying eggs that develop externally. Hookworms like Ancylostoma duodenale and Necator americanus also lay eggs. Trichinella spiralis is another nematode, but it's more about muscle cyst formation.

So putting it all together, the correct answer should be one of the filarial worms, probably Wuchereria bancrofti. The key is that the female worm carries the eggs inside her body until they develop into larvae (microfilariae), which are then released. This fits the ovo-viviparous definition. Therefore, the answer is Wuchereria bancrofti.

**Core Concept**
Ovo-viviparity in nematodes refers to a reproductive strategy where eggs develop into larvae inside the mother’s body but remain nourished by the yolk (not via placental transfer), with larvae being released as free-swimming or infective stages. This is distinct from oviparity (external egg-laying) and viviparity (placental nourishment).

**Why the Correct Answer is Right**
Wuchereria bancrofti, a filarial nematode, is ovo-viviparous. The adult female worm produces microfilariae (larvae) within its body, which are released into the host’s bloodstream. These microfilariae are ingested by mosquitoes during blood meals, completing the life cycle. The internal development of larvae (from egg to larva) within the mother worm without external hatching is the hallmark of ovo-viviparity.

**Why

✓ Correct Answer: C. Strongyloides stercoralis