Final answer:
Mannose-binding lectin is an opsonin that marks pathogens for phagocytosis, enhancing the immune response; therefore, the statement is true.
Step-by-step explanation:
Mannose-binding lectin is indeed an example of an opsonin. Opsonins are molecules that enhance phagocytosis by marking antigens, such as pathogenic bacteria, so they can be more easily recognized and engulfed by phagocytic cells such as neutrophils, macrophages, and dendritic cells. Mannose-binding lectin recognizes specific carbohydrate patterns on the surface of pathogens, and upon binding, it activates the lectin pathway of complement activation, leading to opsonization of the pathogen. Therefore, the student's statement that mannose-binding lectin is an example of an opsonin is true.