Final answer:
An aponeurosis is a thin, flattened sheet that serves as an attachment for muscles, distinguishing it from cord-like tendons by its broad surface area.
Step-by-step explanation:
A tendon that forms a thin, flattened sheet is called an aponeurosis. This structure is a broad, tendon-like sheet that serves as a strong, flat, fibrous attachment for muscles. An example of an aponeurosis is the broad sheet of connective tissue in the lower back that the latissimus dorsi muscles (the "lats") fuse into.
Unlike regular tendons, which are more cord-like, aponeuroses have a wide surface area and attach muscles to the parts they act upon, typically bones. This design allows them to spread the force of muscular contractions over a larger area.
An aponeurosis is a tendon that forms a thin, flattened sheet. It is a broad, tendon-like structure that connects muscles to bone or other muscles, allowing for the transfer of forces. One example of an aponeurosis is the broad sheet of connective tissue in the lower back that the latissimus dorsi muscles fuse into.
Therefore the the correct answer is B) Aponeurosis.