Final answer:
Connective tissues contain three main types of extracellular protein fibers: collagen fibers providing tensile strength, elastic fibers offering flexibility, and reticular fibers creating a supportive mesh.
Step-by-step explanation:
The three types of extracellular protein fibers found in connective tissues are collagen fibers, elastic fibers, and reticular fibers. Collagen fibers are thick and strong, providing great tensile strength which is crucial for the tissue's integrity, making sure it does not tear easily. Elastic fibers, primarily made from the protein elastin, are known for their flexibility, being able to stretch and then return to their original shape which helps tissues maintain their resilience. Lastly, reticular fibers are composed of thin collagen strands that form a supportive mesh within the tissue, offering a supportive framework for the connective tissue and the organs it is associated with.