**Core Concept**
The presence of ova in stool is a diagnostic indicator of parasitic infections, such as hookworm, roundworm, and tapeworm infestations. The identification of ova in stool is a critical step in diagnosing parasitic infections, which can cause a range of symptoms including gastrointestinal disturbances, malabsorption, and anemia.

**Why the Correct Answer is Right**
The correct answer is determined by considering the diagnostic utility of ova in stool for various parasitic infections. In the case of amoebiasis, caused by Entamoeba histolytica, the presence of cysts or trophozoites in stool is the primary diagnostic indicator. However, the presence of ova in stool is not a reliable indicator of amoebiasis, as these parasites have a different lifecycle and diagnostic characteristics.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because ova in stool are indeed diagnostic for hookworm and roundworm infestations, which are common parasitic infections.
* **Option C:** This option is incorrect because ova in stool are also diagnostic for tapeworm infestations, such as Taenia saginata and Taenia solium.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the presence of ova in stool is not diagnostic for amoebiasis, and a definitive diagnosis requires the identification of cysts or trophozoites in stool, or the demonstration of an amoebic infection in tissue samples.

**Correct Answer:** D.