Assertion : Knee joint is the hinge joint.
Reason: Femur , patella and fibula are associated with the knee joint.
A) Both assertion and reason are correct and reason is the correct explanation for assertion.
B) Both assertion and reason are correct but reason is not the correct explanation for assertion.
C) Assertion is correct but reason is incorrect
D) Both assertion and reason are incorrect

Hint:The knee moves through the large muscles of the thigh. The knee works to enable the leg to move and is critical for normal walking. Normally, the knee flexes to 135 degrees at most and extends to 0 degrees.

Complete answer:
The knee joint is a synovial joint of the hinge type, which primarily enables flexion and extension (and a small degree of medial and lateral rotation). Articulations between the patella, femur and tibia form it.
One of the largest and most complicated joints in the body is the knee. The knee joins the shin bone (tibia) with the thigh bone (femur). The other bones that create the knee joint are the smaller bone that runs alongside the tibia (fibula) and the kneecap (patella).The knee bones are connected by tendons to the muscles of the leg that move the knee joint.
The knee bones are joined by ligaments and give stability to the knee:
>The anterior cruciate ligament prevents the femur (or the tibia sliding forward on the femur) from sliding backward on the tibia.
>The posterior cruciate ligament prevents the femur (or tibia from sliding backwards on the femur) from sliding forward on the tibia.
>The medial and lateral collateral ligaments prevent side-to - side sliding of the femur.
>Joints are points of contact between the bones or the cartilage of the bones.
>Between two or more bones, hinge joints are formed where the bones can only move along one axis to flex or extend.

Since the knee connects the thigh with the forearm, the femur, patella, and fibula are connected with the knee joint and consist of two joints, One between the tibia and femur (tibiofemoral joint) and one between the patella and femur (patellofemoral joint).

Thus the correct answer is option (B) i.e, Both assertion and reason are correct but reason is not the correct explanation for assertion.

Note:Hinge joints are a form of joint that acts like the hinge on a door, allowing bones to travel back and forth along other planes in one direction with minimal movement. Hinge joints are found in the thumbs, toes, elbows, knees , and ankles.Hinge joints are complex and involve various tissues and muscles. In different sections of these joints, osteoarthritis and trauma can cause pain and dysfunction.