**Core Concept**
Taenia saginata, also known as the beef tapeworm, is a parasitic flatworm that requires a specific intermediate host to complete its life cycle. The intermediate host is a ruminant animal where the larval stage of the parasite develops before it can infect a human host.

**Why the Correct Answer is Right**
The correct intermediate host of Taenia saginata is cattle. When an infected human consumes undercooked beef containing the cysticercus stage of the parasite, the larvae develop into adult tapeworms in the human intestine. Cattle ingest the eggs of the tapeworm, which then develop into cysticerci in the animal's muscles. Humans become infected by consuming contaminated beef.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Toxocara cati is a parasite that affects cats, not cattle, and is not related to Taenia saginata.

**Option B:** This option is incorrect because Trichinella spiralis is a parasite that causes trichinosis and is typically found in pork, not beef.

**Option C:** This option is incorrect because Echinococcus granulosus is a parasite that causes hydatid disease and is typically found in dogs, not cattle.

**Option D:** This option is incorrect because Ascaris lumbricoides is a parasite that affects humans and is not related to Taenia saginata.

**Clinical Pearl / High-Yield Fact**
It is essential to note that Taenia saginata can be prevented by proper cooking of beef, as the parasite is killed by heat. This highlights the importance of food safety in preventing parasitic infections.

**Correct Answer: C. Cattle.**