A metal sample is pulled by a force that rises to a peak value and then falls again to zero. The force-extension graph for the sample is shown below. As the sample shortens, it retraces the same force-extension curve that it followed while being stretched. What happens to the metal between X and Y?
- Aboth elastic and plastic
- Bnot elastic and not plastic
- Cplastic but not elastic
- Delastic but not plastic