What type of protein is elastin primarily responsible for?

Elastin is primarily responsible for elasticity in connective tissues, which allows structures such as skin, blood vessels, and lungs to stretch and return to their original shape. This protein is crucial for maintaining the flexibility and resilience of these tissues, enabling them to withstand various mechanical stresses without losing their integrity. The presence of elastin ensures that tissues can expand and contract efficiently, providing functionality in various physiological processes. While strength, hydration, and support are important aspects of connective tissue, elastin's unique function is specifically geared towards enabling elasticity, making option B the correct choice.