## Core Concept
Giardiasis is an intestinal infection caused by the **Giardia lamblia** parasite, which is a flagellated protozoan. It affects the small intestine and can lead to symptoms such as diarrhea, greasy stools, and abdominal cramps. Giardiasis is commonly spread through contaminated water or food.

## Why the Correct Answer is Right
The correct answer, option D, being the exception, implies that three of the statements regarding giardiasis are true, and one is false. Without the specific details of each option, we can infer that the correct answer relates to a characteristic, transmission method, diagnostic feature, or treatment approach that does not align with established facts about giardiasis.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specifics, we can't directly address why A is incorrect, but if A states a true characteristic of giardiasis, such as its transmission via contaminated water or its symptomatology, then it would be a correct statement about the disease.
- **Option B:** Similarly, if B presents a true aspect of giardiasis, such as the use of certain diagnostic tests (e.g., microscopy, antigen detection) or the role of immune responses in controlling the infection, its correctness would depend on the accuracy of the statement regarding giardiasis.
- **Option C:** This option would also need to be evaluated based on its accuracy in describing giardiasis. If it presents a false statement, such as an incorrect treatment approach or a misconception about the parasite's life cycle, then it would be the incorrect option.

## Clinical Pearl / High-Yield Fact
A key point to remember about giardiasis is that it can cause **traveler's diarrhea** and is often associated with consumption of contaminated water or food. A classic clinical pearl is that giardiasis can lead to **malabsorption**, particularly of fats, leading to steatorrhea (fatty stools).

## Correct Answer: D.