What muscle is pictured below?

Rationale:
A. Humerus is the long bone of the upper arm, extending from the shoulder to the elbow. While it is long and strong, it is not the longest bone in the body.
B. Ulna is one of the two forearm bones, located on the medial side (little finger side). It is relatively slender and much shorter than the femur.
C. Known as the shin bone, it is the second longest bone in the body and bears most of the body’s weight in the lower leg. However, it is still shorter than the femur.
D. The femur, or thigh bone, extends from the hip to the knee and is the longest, strongest, and heaviest bone in the human body. It supports much of the body’s weight, allows locomotion, and provides attachment points for many large muscles.

Rationale:
A. Cartilaginous joints are connected entirely by cartilage (such as the pubic symphysis or intervertebral discs). They allow limited movement but do not make up the majority of joints in the body.
B. Fibrous joints are connected by dense connective tissue and are mostly immovable (such as sutures in the skull). They are important for stability but are relatively few compared to synovial joints.
C. Synovial joints are the most numerous type in the body and allow the greatest range of motion. Examples include the shoulder, hip, knee, and elbow. They are characterized by the presence of a joint cavity filled with synovial fluid, articular cartilage, a synovial membrane, and supporting ligaments. Their structure allows movements such as gliding, rotation, flexion, extension, abduction, and adduction.
D. Synarthroses refers to immovable joints (such as sutures), which are a subset of fibrous joints. They provide stability but are not the majority type of joint in the body.