Which one of the following statements regarding muscle contraction and relaxation is correct?
1
It involves movement of \(Xn^{++}\) ion
2
It involves \(Ca^{++}\)ion if blood
3
It involves release of \(Ca^{++}\) from sarcoplasmic reticulum (SR) and pumping \(Ca^{++}\) back in SR
4
More than one of the above
5
None of the above