Final answer:
The proteins found in myofibrils that form the sections known as sarcomeres are actin and myosin, with actin being the thin filament and myosin being the thick filament. These are essential for muscle contraction.
Therefore, option a is correct
Step-by-step explanation:
The myofibrils that form your muscle fibers are divided into sections called sarcomeres that contain two different types of proteins (myofilaments) called actin and myosin. Option (a) Actin; Myosin is the correct answer. These myofilaments are vital for muscle contraction and give skeletal muscle fibers their striated appearance. Actin filaments are thinner and are sometimes referred to as thin filaments, while myosin filaments are thicker and are also known as thick filaments. Every sarcomere runs from one Z line to the next, and the overlapping of these filaments is crucial for muscle movement.