This granulocyte is known for attacking parasites and moderating allergic reactions.

The correct choice, identified as the eosinophil, is a type of granulocyte that plays a crucial role in the immune response against parasitic infections as well as in the modulation of allergic reactions. Eosinophils contain granules rich in enzymes and proteins that are effective at combating parasites, particularly multicellular organisms such as helminths. When eosinophils are activated, they release these granules, which can damage the cell membranes of parasites, aiding in their destruction.

In the context of allergic reactions, eosinophils can also contribute to inflammation and tissue damage in response to allergens. They produce mediators and cytokines that can exacerbate the allergic response, thus helping to regulate the overall reaction and potentially contributing to conditions such as asthma and hay fever.

Understanding the role of eosinophils provides insight into their dual functions in both defending against parasitic infections and regulating hypersensitivity responses, which is what makes them unique among the different types of granulocytes.