## Core Concept
The question tests the understanding of chemical mediators involved in the recruitment and activation of neutrophils during inflammation. Neutrophils are a type of white blood cell crucial in the innate immune response, particularly against bacterial infections. Various chemical mediators, including cytokines, chemokines, and leukotrienes, play significant roles in their mobilization and function.

## Why the Correct Answer is Right
Interleukin-2 (IL-2) is primarily involved in the growth, proliferation, and survival of T cells. While it plays a critical role in the immune response, its primary function is not directly related to the recruitment or activation of neutrophils. In contrast, the other options listed are directly involved in neutrophil functions:
- **C5a** is a potent chemotactic agent for neutrophils, produced during the activation of the complement system.
- **Leukotriene B4 (LTB4)** is a chemotactic factor for neutrophils, derived from arachidonic acid through the lipoxygenase pathway.
- **Interleukin-8 (IL-8)** is a chemokine that acts as a potent chemoattractant for neutrophils.

## Why Each Wrong Option is Incorrect
- **Option A (C5a):** This is a fragment of the complement component C5 and acts as a potent chemotactic factor for neutrophils. Therefore, it is involved in neutrophil recruitment.
- **Option B (Leukotriene B4):** This is a product of arachidonic acid metabolism and serves as a chemotactic agent for neutrophils. Hence, it is directly involved in neutrophil function.
- **Option D (Interleukin-8):** This chemokine is known for its role in inducing chemotaxis in target cells, primarily neutrophils but also other granulocytes, causing them to migrate toward the site of infection.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while IL-2 is crucial for T-cell responses, its direct role in neutrophil activation or recruitment is minimal compared to the other mediators listed, which are more directly involved in the acute inflammatory response and the recruitment of neutrophils.

## Correct Answer Line
**Correct Answer: B. Interleukin-2.**