**Core Concept**
Invasive amoebiasis, caused by Entamoeba histolytica, is a serious infection that involves the invasion of intestinal or extraintestinal tissues. The diagnosis of invasive amoebiasis requires a combination of clinical evaluation, laboratory tests, and imaging studies.

**Why the Correct Answer is Right**
The correct answer is **Option D:** Serological tests, specifically indirect hemagglutination (IHA) or enzyme-linked immunosorbent assay (ELISA), are useful for detecting antibodies against E. histolytica in the serum. These tests can confirm the diagnosis of invasive amoebiasis, particularly in cases where the amoeba is not present in the stool or tissue samples. Serological tests are also useful for detecting asymptomatic carriers and for monitoring the response to treatment.

**Why Each Wrong Option is Incorrect**
* **Option A:** Stool examination for cysts and trophozoites is useful for diagnosing intestinal amoebiasis, but it may not detect invasive amoebiasis.
* **Option B:** Endoscopy may reveal ulcers and inflammation in the intestine, but it is not a definitive diagnostic test for invasive amoebiasis.
* **Option C:** Imaging studies, such as CT or ultrasound, may show abnormalities in the liver or other organs, but they are not specific for invasive amoebiasis.

**Clinical Pearl / High-Yield Fact**
It is essential to note that serological tests may not differentiate between E. histolytica and E. dispar, which is a non-pathogenic amoeba. Therefore, a positive serological test should be confirmed by stool examination or other diagnostic tests.

**Correct Answer:** D. Serological tests are useful for detecting antibodies against E. histolytica in the serum.