**Core Concept**
The question is testing the student's knowledge of parasite transmission pathways, specifically the distinction between soil-transmitted and non-soil-transmitted parasites. This requires an understanding of the life cycles and transmission mechanisms of various parasites.

**Why the Correct Answer is Right**
Tapeworms are typically transmitted through the fecal-oral route, where the parasite eggs are ingested through contaminated food or water, but not through soil. In contrast, tapeworms can also be transmitted through the ingestion of undercooked meat containing the cysticercus stage. The primary mode of transmission of tapeworms is not through soil, which is the key to understanding why this option is correct. This is in contrast to other parasites like hookworms, which are transmitted through contaminated soil.

**Why Each Wrong Option is Incorrect**
**Option A:** Pinworms are transmitted through fecal-oral contamination, but they can also be transmitted through contact with contaminated soil or surfaces, making this option incorrect.
**Option B:** Hookworms are a classic example of a soil-transmitted parasite, where the eggs are ingested through contaminated soil, making this option incorrect.
**Option D:** Roundworms are also transmitted through fecal-oral contamination, but they can be transmitted through contaminated soil, making this option incorrect.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that while tapeworms are not typically transmitted through soil, their life cycles can involve complex transmission pathways, including ingestion of contaminated food or water, making it crucial to maintain proper hygiene and sanitation practices to prevent infection.

**✓ Correct Answer: C. Tapeworm**