The connective tissue which contains many collagenous fibers embedded within a firm matrix is?

The correct answer is cartilage. Cartilage is a type of connective tissue known for its firm, yet flexible matrix that contains a high concentration of collagenous fibers, which provide strength and support. This unique composition allows cartilage to maintain its shape while also being able to absorb shock, making it essential in areas such as joints, the ribcage, and the ear.

In contrast, blood does not contain collagenous fibers in a matrix; instead, it is a liquid connective tissue that primarily transports nutrients and waste. Adipose tissue, while a connective tissue, mainly consists of fat cells that store energy and do not have a matrix rich in collagen fibers. Elastin refers to a type of protein found in connective tissues that provides elasticity and resilience, but it is not itself a tissue type like cartilage is. Therefore, the defining characteristics of cartilage, including its matrix and fiber composition, make it the correct answer.