Movement - core: Quadriceps.

Movement - core: Quadriceps.

• A. Quadriceps
• B. Hamstring Complex
• C. Deltoids
• D. Adductor Complex

Answer: (A)

The main idea is identifying the primary muscle group responsible for the movement. In actions that hinge on knee extension and lifting the body from a lower position, the quadriceps are the prime movers. The quadriceps (four muscles on the front of the thigh) generate the force to straighten the knee, which drives many common lower-body movements like squats and leg presses. The hamstrings act more as stabilizers and antagonists, assisting with controlled knee flexion and hip actions but not providing the main knee-extension force here. The deltoids are shoulder muscles and don’t contribute to this lower-body movement, and the adductor complex mainly handles hip adduction and stabilization rather than extending the knee. So the quadriceps best fit the role for this movement.

The main idea is identifying the primary muscle group responsible for the movement. In actions that hinge on knee extension and lifting the body from a lower position, the quadriceps are the prime movers. The quadriceps (four muscles on the front of the thigh) generate the force to straighten the knee, which drives many common lower-body movements like squats and leg presses. The hamstrings act more as stabilizers and antagonists, assisting with controlled knee flexion and hip actions but not providing the main knee-extension force here. The deltoids are shoulder muscles and don’t contribute to this lower-body movement, and the adductor complex mainly handles hip adduction and stabilization rather than extending the knee. So the quadriceps best fit the role for this movement.