In the given stress-strain graph,what does point $D$ indicate?

The diagram shows a force-extension graph for a rubber band. Consider the following statements:
$I.$ It will be easier to compress this rubber than expand it.
$II.$ Rubber does not return to its original length after it is stretched.
$III.$ The rubber band will get heated if it is stretched and released.
Which of these can be deduced from the graph?

The figure shows the stress-strain curve for a given material. What are $(a)$ Young's modulus and $(b)$ approximate yield strength for this material?

The graph below represents a typical stress-strain curve for a metal. Identify the point on the graph that is the ultimate tensile strength of the material.

The potential energy $U$ between two molecules as a function of the distance $X$ between them is shown in the figure. The two molecules are

Plot a stress $\to$ strain curve for a metal and explain.