**Core Concept**
The underlying principle being tested is the identification of ova based on their flotation characteristics in saturated saline solution, which is a diagnostic tool in parasitology. This method exploits the differences in density between various types of ova and the saline solution.

**Why the Correct Answer is Right**
Since the correct answer is not provided, let's discuss the general principle: ova that float in saturated saline are typically those with a lower density than the solution, often indicating the presence of certain parasitic infections. The flotation technique is commonly used to detect ova of parasites such as *Ascaris lumbricoides*, *Trichuris trichiura*, and hookworms.

**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific answer choices, it's challenging to address each option directly. However, incorrect options would typically include ova that do not float in saturated saline, such as those from parasites that require a different diagnostic approach.
**Option B:** Similarly, without the specific text, we can't directly refute this choice, but it would be incorrect if it described ova that sink rather than float.
**Option C:** This option would be incorrect if it represents ova that are identified through a different method or have a different characteristic.
**Option D:** Likewise, this would be an incorrect choice if it doesn't match the flotation behavior in question.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the flotation method is sensitive for detecting certain parasites but may not be universally applicable to all types of ova. It's essential to combine this technique with other diagnostic approaches for comprehensive parasitological examinations.

**Correct Answer:** Correct Answer: D. *Ascaris*.