Question

the ______ relax(es) the muscles.
muscle spindles
myofibrils
muscle fibers
golgi tendon organ

Explanation:

To solve this, we analyze each option:

• Muscle spindles: Detect muscle stretch, not relax muscles.
• Myofibrils: Contractile elements in muscle fibers, involved in contraction, not relaxation.
• Muscle fibers: Composed of myofibrils, mainly for contraction.
• Golgi tendon organ: Monitors muscle tension and triggers a reflex to relax muscles to prevent injury.

Answer:

D. Golgi tendon organ