All float in a saturated salt solution except -a) Clonorchis sinensisb) Fertilised eggs of ascarisc) Larva of strongyloidesd) Trichuris trichura

**Core Concept:** Saturated salt solution is a solution in which all the available sites for solute molecules to dissolve are occupied by the solute molecules, rendering further addition of solute molecules impossible. In this context, the solute molecules are ions from the salt. When a biological specimen is placed in a saturated salt solution, it will either dissolve (if it is a soluble salt) or not dissolve (if it is an insoluble salt or a biological entity like eggs or larvae).

**Why the Correct Answer is Right:**

The correct answer is "Clonorchis sinensis", "Fertilized eggs of Ascaris", and "Larva of Strongyloides". These are biological entities, namely parasites, which are not soluble salts. They generally do not dissolve in a saturated salt solution, as they lack the necessary ions to interact with the saturated solution and dissolve. In contrast, "Trichuris trichura" is a soluble salt, hence it will dissolve in a saturated salt solution.

**Why Each Wrong Option is Incorrect:**

Option A (Fertilized eggs of Ascaris) and Option D (Trichuris trichura) are biological entities, specifically parasites, which are not salts. These entities do not dissolve in a saturated salt solution due to the lack of ions for interaction with the salt solution.

Option B (Larva of Strongyloides) and Option C (Clonorchis sinensis) are also biological entities, in this case, parasites. These parasites do not dissolve in a saturated salt solution, as they lack the necessary ions to interact with the salt solution and dissolve.

**Clinical Pearl / High-Yield Fact:**

Understanding the solubility of biological entities in saturated salt solutions is crucial in clinical practice, particularly in histopathology and parasitology. This knowledge helps in correctly identifying and distinguishing between various parasites and soluble salts on histopathological slides prepared from patient samples. A thorough understanding of this concept will aid in accurate diagnosis and appropriate treatment recommendations for patients with parasitic infections.