A wire exhibits both elastic and plastic behaviour. When the load on it is increased gradually, the extension changes with load as indicated by line $OXY$. The load is then removed, as shown by line $YZ$. This results in areas $P$, $Q$ and $R$ being formed on the graph. Which area shows the greatest elastic potential energy stored in the wire?
- A$P$
- B$Q$
- C$Q + R$
- D$R$