**Core Concept**
The question is testing the student's knowledge of the life cycle of Taenia, a type of tapeworm. The larval form of Taenia is an important concept in parasitology, as it is the stage that infects humans. The correct answer will reveal the stage in the life cycle of Taenia that is responsible for human infection.

**Why the Correct Answer is Right**
The larval form of Taenia is called a cysticercus. This stage is formed when the egg of Taenia is ingested by a suitable intermediate host, usually a pig. The egg hatches into a six-hooked oncosphere that penetrates the intestinal wall and migrates to the muscles, where it develops into a cysticercus. The cysticercus is the stage that infects humans when undercooked meat containing the parasite is consumed.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the term "cyst" refers to a fluid-filled sac, whereas the larval form of Taenia is a parasitic stage that infects the muscles.
* **Option B:** This option is incorrect because the term "hydatid" refers to a type of cysticercus found in Echinococcus, a different type of tapeworm.
* **Option C:** This option is incorrect because the term "metacestode" is a general term for the larval stage of a tapeworm, but it is not specific to Taenia.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that Taenia solium is a zoonotic parasite, meaning it can be transmitted from animals to humans. The cysticercus stage can infect various tissues, including the brain, leading to neurocysticercosis, a serious neurological condition.

**Correct Answer: C. cysticercus**