**Core Concept**
The question is testing the identification of a specific nematode parasite that inhabits the human caecum and appendix. This requires knowledge of the parasitology of the gastrointestinal tract.

**Why the Correct Answer is Right**
The correct nematode parasite that resides in the caecum and appendix is Ascaris lumbricoides is incorrect because it typically resides in the small intestine. However, the correct answer is Ascaris is not the correct answer we are looking for. The correct answer is **Enterobius vermicularis**. This parasite is known to cause enterobiasis and is commonly found in the human caecum and appendix. The mechanism of its residence in these areas is thought to be related to its ability to migrate through the intestinal wall and attach itself to the mucosa.

**Why Each Wrong Option is Incorrect**
**Option A:** Ascaris lumbricoides - While this parasite does reside in the human intestine, it is typically found in the small intestine, not the caecum and appendix.
**Option B:** Strongyloides stercoralis - This parasite is also found in the human intestine, but it is typically associated with the small intestine and does not typically reside in the caecum and appendix.
**Option C:** Ancylostoma duodenale - This parasite is a hookworm that resides in the human small intestine and does not typically inhabit the caecum and appendix.

**Clinical Pearl / High-Yield Fact**
It's worth noting that Enterobius vermicularis is a common cause of gastrointestinal symptoms in humans, particularly in children and individuals with poor hygiene practices.

**Correct Answer: D. Enterobius vermicularis**