Which muscles are primarily responsible for forward motion during

Correct answer: D) Quadriceps.
The muscles primarily responsible for forward motion during walking on level ground are the quadriceps.

- Quadriceps: These muscles are located on the front of the thigh and consist of four muscles (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius). They play a crucial role in extending the knee, which is essential for pushing off the ground and propelling the body forward during the walking cycle.

By contracting the quadriceps, especially during the extension phase of the leg while walking, they generate the force necessary to move the body forward. This action is known as concentric contraction, where the muscle shortens to produce movement.

In contrast, the other muscle groups mentioned:
- Glutes: These muscles are more involved in hip extension rather than the primary forward motion during walking.
- Hamstrings: These muscles are responsible for flexing the knee and extending the hip, playing a role in the swinging phase of walking rather than forward propulsion.
- Gastrocnemius and soleus: These muscles are mainly involved in plantar flexion of the ankle, which is important for pushing off the ground but not the primary driving force for forward motion during walking on level ground.