What type of joints are most commonly found at the knees and wrists?

Movable joints, also known as synovial joints, are the most common type of joint in the human body and allow for a wide range of movement. They are distinguished by a synovial cavity filled with synovial fluid, which aids in reducing friction and wear at the joint.

The knees and wrists are examples of movable joints, specifically hinge joints. Hinge joints, like the knee joint, allow movement in only one plane, such as flexion and extension. The wrist joint, on the other hand, is a complex synovial joint with multiple degrees of freedom, allowing for movements such as flexion, extension, abduction, and adduction.

Hence, the correct option is a movable joint.