The extracellular matrix in connective tissue primarily consists of:
- Ground substance
- Protein fibers
So, the correct answer is d) protein fibers and ground substance.
Explanation: Connective tissue is unique because it has a significant amount of extracellular matrix compared to the cellular components. The extracellular matrix is composed of two main elements: the ground substance, which is a gel-like material that fills the space between cells, and the protein fibers, which provide strength and elasticity to the tissue. These protein fibers include collagen, elastin, and reticular fibers. The combination of these components allows connective tissues to perform various functions, including support, binding other tissues together, and providing flexibility to the body.