**Core Concept**
Giardia lamblia is a protozoan parasite that causes giardiasis, a waterborne disease. It possesses flagella, which are essential for its motility and attachment to the intestinal mucosa of its host.

**Why the Correct Answer is Right**
Giardia lamblia has a unique characteristic among protozoa, possessing four pairs of flagella. Two pairs of flagella are located at the anterior end, one pair is located near the ventral sucker, and the fourth pair is located near the posterior end. The anterior flagella are used for forward movement, while the posterior flagella are involved in attachment to the intestinal mucosa. The ventral sucker flagella help in anchoring the parasite to the epithelial cells.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Giardia lamblia does not possess only one pair of flagella. Its unique characteristic is the presence of multiple pairs of flagella.
**Option B:** This option is incorrect because Giardia lamblia does not possess six pairs of flagella. The correct number is four pairs.
**Option C:** This option is incorrect because Giardia lamblia does not possess eight pairs of flagella. The correct number is four pairs.
**Option D:** This option is incorrect because Giardia lamblia does not possess two pairs of flagella. The correct number is four pairs.

**Clinical Pearl / High-Yield Fact**
Remember that Giardia lamblia has a unique flagellar arrangement that allows it to attach to the intestinal mucosa and cause giardiasis. This is a key point to remember when considering the pathogenesis of this parasite.

**Correct Answer:** B. 4