Question

is/are an important bridge between the innate and adaptive immune systems. macs tlrs complement proteins natural killer cells

Explanation:

Macrophages (MACs) are important in linking innate immunity (by detecting pathogens) to adaptive immunity (by presenting antigens to activate T - cells, etc.). TLRs (Toll - like receptors) are mainly for pathogen recognition in innate immunity. Complement proteins are part of the innate immune response cascade. Natural killer cells are innate immune cells for killing infected cells. So MACs act as the bridge between innate and adaptive immune systems.

Answer:

A. MACs