Which muscles are NOT primary flexor of knee
A. Gastrocnmius
B. Plantaris
C. Vastus Medialis
D. Rectus Femoris
E. Vastus Lateralis
Choose the correct answer from the options given below:

Correct option is D

A. Gastrocnemius: This muscle is a primary flexor of the knee. Although it is often known for its role in plantarflexion at the ankle, it also helps with knee flexion because it crosses the knee joint.
B. Plantaris: This muscle also assists with knee flexion. It is a weak knee flexor and assists with plantarflexion at the ankle.
C. Vastus Medialis: This muscle is part of the quadriceps group and is not involved in knee flexion. It primarily helps with knee extension.
D. Rectus Femoris: This muscle is also part of the quadriceps group, and although it crosses both the hip and knee joints, its primary action is knee extension, not flexion.
E. Vastus Lateralis: Like the Vastus Medialis, the Vastus Lateralis is part of the quadriceps group and is primarily involved in knee extension, not flexion.