Arrange the steps in the correct order to explain how a muscle fiber contracts  

Step 1A nerve impulse moves down and axon and causes the release of acetylcholine.
Step 2Acetylecholine causes the pulse to spread across the surface of the sarcolemma.
Step 3The nerve impulse enters the T Tubules and Sarcoplasmic Reticulum, which stimulates the release of calcium ions.
Step 4Calcium ions combine with troponin, shifting troponin and exposure of the myosin binding sites to the stock.
Step 5ATP breaks ADP + P. The released energy activates the myosin crossings and leads to the slipping of thin stockmilofilament past the thick myosin membrane membranes.
Step 6The sliding of the myofilaments draws the Z lines, the sarcoma shortens, the muscle fiber contract and thus muscle contracts.
Step 7ACh is activated by acetylcholinesterase, which inhibits the nerve impulse conduction across the sarcolemma.
Step 8Nerve impulse is inhibited, calcium ions are actively traced back into the Sarcoplasmic Reticulum, using the energy of the previous ATP degradation.
Step 9The low calcium concentration causes the myosin crossings to separate from the think-in-tensile filaments and return the stockmilofilaments to their relaxed position.
Step 10Sarcomeres return to their rest lengths, relax muscle fibers and relax the muscles.

The answer is a i believe