**Core Concept**
The question is testing the ability to diagnose a parasitic infection based on clinical presentation and a simple diagnostic test. The underlying principle is the identification of intestinal parasites using a tape test, which involves applying transparent tape to the perianal region to collect eggs or ova.

**Why the Correct Answer is Right**
The tape test is a common method for diagnosing enterobiasis, caused by the pinworm *Enterobius vermicularis*. The eggs of this parasite are laid in the perianal region, where they can be collected using transparent tape. The eggs are oval in shape and flattened along one side, making them easily identifiable under a microscope. This characteristic morphology is a key diagnostic feature of enterobiasis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the tape test is not typically used to diagnose infections with *Trichuris trichiura*, the whipworm, which lays eggs in the large intestine.
* **Option B:** This option is incorrect because *Ascaris lumbricoides*, the roundworm, lays eggs in the soil and is typically diagnosed through stool examination rather than the tape test.
* **Option C:** This option is incorrect because *Ancyclostoma duodenale*, the hookworm, lays eggs in the small intestine and is also typically diagnosed through stool examination.

**Clinical Pearl / High-Yield Fact**
The tape test is a simple and effective method for diagnosing enterobiasis, particularly in children. It is essential to instruct parents to place the tape on the perianal region before the child defecates, as this will increase the chances of collecting eggs.

**Correct Answer:** C.