**Core Concept**
Visceral larva migrans (VLM) is a condition characterized by the migration of larvae of a specific nematode through the body's internal organs, leading to various clinical manifestations. It is a type of helminthic infection that primarily affects children.

**Why the Correct Answer is Right**
The condition is caused by the ingestion of eggs of the dog roundworm, *Toxocara canis*, which is commonly found in contaminated soil. When ingested, the eggs hatch into larvae, and the larvae penetrate the intestinal wall and migrate through the body's internal organs, including the liver, lungs, and brain. The larvae evade the host's immune response by producing suppressive molecules, leading to the characteristic clinical manifestations of VLM.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because VLM is not caused by the hookworm *Ancylostoma duodenale*, which primarily causes cutaneous larva migrans.
**Option B:** This option is incorrect because VLM is not caused by the tapeworm *Taenia saginata*, which is typically associated with taeniasis.
**Option C:** This option is incorrect because VLM is not caused by the nematode *Strongyloides stercoralis*, which primarily causes strongyloidiasis.

**Clinical Pearl / High-Yield Fact**
The diagnosis of VLM is often based on a combination of clinical findings, laboratory tests, and imaging studies. A high index of suspicion is required, especially in children who have been exposed to contaminated soil.

**Correct Answer:** D. *Toxocara canis*