What does the binding energy per nucleon show?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range $30$ to $170$.
Reason $R:$ Nuclear force is short-ranged.
In the light of the above statements, choose the correct answer from the options given below:

Write and explain Einstein's theory of special relativity in the context of mass-energy equivalence.

If $m$ is the mass of the $_Z{X^A}$ nucleus,and $m_n$ and $m_p$ are the masses of a neutron and a proton respectively,then which of the following is correct?

In the nuclear reaction,$_1H^2 + _1H^2 \to _0n^1 + _2He^3$. If the binding energy of deuteron is $2.23 \ MeV$ and the $Q$-value of the reaction is $3.27 \ MeV$,then the binding energy of $_2He^3$ is ......... $MeV$.

The binding energy for the following nuclear reactions are expressed in $MeV$.
${ }_2 He ^3+{ }_0 n ^1 \rightarrow{ }_2 He ^4+20 \ MeV$
${ }_2 He ^4+{ }_0 n ^1 \rightarrow{ }_2 He ^5-0.9 \ MeV$
If $X_3, X_4, X_5$ denote the stability of ${ }_2 He ^3, { }_2 He ^4$ and ${ }_2 He ^5$,respectively,then the correct order is: