What components primarily make up the extracellular matrix of connective tissue?

The extracellular matrix (ECM) of connective tissue is predominantly composed of protein fibers and ground substance. Protein fibers, such as collagen and elastin, provide structural support and strength to the tissue, allowing it to withstand various types of stress. Ground substance, on the other hand, consists of a gel-like material that fills the space between the cells and the fibers, facilitating the diffusion of nutrients and waste products while providing a medium for cell communication.

This combination of protein fibers and ground substance is essential for the ECM's functionality in maintaining the integrity and flexibility of connective tissues. It plays a vital role in tissue repair, wound healing, and providing a scaffold for cellular attachment and interaction.

The other options do not accurately represent the primary components of the extracellular matrix. For instance, calcified crystals of minerals and enzymes do not primarily contribute to the matrix's structure in connective tissues. Keratined cells are more relevant to epithelial tissues rather than connective tissue, and while enzymes and membranous organelles are important for cellular metabolism, they do not form part of the extracellular matrix. Thus, the accurate representation of the ECM is reflected in the choice of protein fibers and ground substance.