Q.The characteristic sequence used in PNF (proprioceptive neuromuscular facilitation) stretching is:

PNF stretching is a clinical and athletic technique that exploits the nervous system's own reflexes to achieve a deeper stretch than static stretching alone. The core idea is to first fatigue or inhibit the muscle's stretch reflex, then immediately lengthen it. The standard sequence is an isometric contraction of the target muscle against resistance (which activates the Golgi tendon organ and relaxes the muscle), followed by a relaxation phase, and then a passive stretch into the new range of motion. This is often remembered as "contract-relax" or "hold-relax." …

PNF stretching is one of the most effective methods for improving flexibility, and it works by exploiting a built-in safety mechanism in your muscles. When you stretch a muscle too quickly or too far, your nervous system triggers the stretch reflex — the muscle contracts to protect itself from tearing. That reflex is what stops you from making progress in a static stretch.

The genius of PNF is that it turns off that reflex. By having you voluntarily contract the muscle first, you fatigue the sensory organs (Golgi tendon organs) that monitor tension. Those organs then send a signal to the muscle to relax — a phenomenon called autogenic inhibition. Once the muscle is in that relaxed state, you can stretch it further than you could before, and with less risk of injury.

The sequence is always: contract the target muscle against resistance, then relax it, then immediately stretch it. That's the three-step rhythm. The contraction is usually held for about 6–10 seconds, the relaxation is brief (2–3 seconds), and the final stretch is held for 15–30 seconds. The partner or strap provides the resistance during the contraction and assists with the stretch.

Now look at the options given: …