**Core Concept**
The diagnosis of Ascaris lumbricoides infection involves identifying the parasite or its components in a patient's sample. Ascaris is a large roundworm that can cause intestinal obstruction, respiratory problems, and other complications.

**Why the Correct Answer is Right**
The specific diagnosis of Ascaris is typically made by detecting the adult worm in the patient's stool. This is because the adult worm is large enough to be visualized with the naked eye or under a microscope, making it a reliable indicator of infection. The adult worm can be identified by its characteristic shape, size, and features, such as a distinct head and tail.

**Why Each Wrong Option is Incorrect**
* **Option A:** Adult worm in stool is the correct answer, so this option is incorrect.
* **Option B:** Egg detection is a method used to diagnose Ascaris infection, but it is not specific, as eggs can be present in the stool for years after the infection has cleared.
* **Option C:** Antigen detection is a method used to diagnose various parasitic infections, but it is not the most specific or reliable method for diagnosing Ascaris.
* **Option D:** Antibody detection is a method used to diagnose infections, but it is not specific for Ascaris, as antibodies can remain present for years after the infection has cleared.
* **Option E:** Skin test is not a reliable method for diagnosing Ascaris infection, as it can produce false-positive results and is not specific for this parasite.

**Clinical Pearl / High-Yield Fact**
The presence of Ascaris in the stool can lead to intestinal obstruction, especially in children. It is essential to diagnose and treat Ascaris infection promptly to prevent complications.

**Correct Answer:** a) Adult worm in stool