Smooth and cardiac muscle operates under involuntary control, whereas skeletal muscle operates under voluntary control.

Rationale:
A. This is the visible part of the hair above the skin’s surface. It is made of keratinized cells and does not have the ability to contract or move.
B. This is the portion of the hair located below the surface of the skin within the follicle. Like the shaft, it does not control hair movement.
C. The follicle is the structure in the dermis that surrounds and nourishes the hair root, providing the base for hair growth. While important for hair formation, it does not cause the hair to stand erect.
D. The arrector pili are small bands of smooth muscle fibers attached to hair follicles. When these muscles contract (in response to cold, fear, or emotional stimuli), they pull the hair follicle upright, causing the hair to "stand on end" (a phenomenon known as piloerection or "goosebumps").

Rationale:
A. Flexion refers to decreasing the angle between two body parts, such as bending the elbow or knee.
B. Extension is the opposite of flexion, involving an increase in the angle between body parts, such as straightening the arm or leg.
C. Abduction is the movement of a body part away from the midline of the body, like lifting the arm or leg sideways.
D. Adduction involves moving a body part toward the midline of the body, such as bringing the arms back down to the sides or crossing the legs together. This movement is essential for coordinated limb positioning and maintaining balance.