What Is an Important Part of the Role Played by Macrophages

What is an important part of the role played by macrophages during maintenance and renewal of strong extracellular fibers in connective tissue?

A) Storage for a major energy source needed for ECM maintenance
B) Production of specific collagen subunits
C) A sentinel function against invaders entering the ECM
D) Secretion of MMPs
E) Presentation of antigens important for assembly of collagen bundles