Final answer:
IgG is the molecule primarily responsible for the initial recruitment of neutrophils to an inflammatory site by binding to antibody receptors on mast cells, leading to degranulation, complement activation, and subsequent neutrophil chemotaxis.
Step-by-step explanation:
The initial recruitment of neutrophils to an inflammatory site involves several steps and molecules. Among the options provided, IgG is the molecule that plays a key role in this process. IgG can bind to antibody receptors on localized mast cells, which results in mast-cell degranulation. This degranulation and complement activation lead to the production of pro-inflammatory molecules such as C3a and C5a. These pro-inflammatory molecules contribute to increased blood-vessel permeability, which, along with chemotactic factors like leukotrienes and chemokines, assists in the chemotactic recruitment of neutrophils and macrophages to the site of inflammation. This chemotactic movement of neutrophils specifically is known as phagocyte chemotaxis and it's a key element in the body's immune response to infection or tissue damage.