Which of the following describes the primary role of eosinophils?

Eosinophils primarily play a critical role in mediating allergic reactions and combating parasitic infections. They are involved in the regulation of allergic responses by releasing granules that contain substances like histaminase and other enzymes that can modulate inflammation and tissue responses associated with allergies. In the context of allergic reactions, eosinophils help to reduce inflammation and tissue damage, contributing to the resolution of allergic symptoms.

In addition to their regulatory role in allergies, eosinophils can also respond to parasitic infections by directly attacking the parasites and contributing to inflammatory responses. Their unique granules contain toxic proteins that are effective against larger parasites too big for phagocytosis. Thus, while taking part in immune responses, their primary description aligns most closely with the regulation and mediation of allergic responses.