Answer: b, c The proliferative phase of wound healing begins with the formation of a provisional matrix of fibrin and fibronectin as part of the initial clot formation. Initially, the provisional matrix is populated by macrophages; however, by day three fibroblasts appear in the fibronectin-fibrin framework and initiate collagen synthesis. Fibroblasts proliferate in response to growth factors become the dominant cell type during this phase. Growth factors produced by macrophages simultaneously induce angiogenesis which results in the ingrowth and proliferation of endothelial cells, forming new capillaries. This neovascularity is visible through the epithelium and gives the wound a pink or purple-red appearance. Collagen is the dominant structural molecule in the wound matrix and in the final scar. Collagen is synthesized into an organized cable-like network in a multi-step process with both intra- and intercellular components. The collagen molecule has quantities of two unique amino acids, hydroxyproline and hydroxylysine. The hydroxylization processes which form these amino acids require ascorbic acid (vitamin C) and is necessary for the subsequent stabilization and cross linkage of collagen. The principal collagen type scar is type 1, with lesser amounts of type 3 collagen also present