Which of the following is used as a moderator in nuclear reactors?

Consider the following statements $A$ and $B$. Identify the correct choice in the given answer.
$A$. $p-n, p-p$ and $n-n$ forces between nucleons are not equal and charge dependent.
$B$. In a nuclear reactor, the fission reaction will be in an accelerating state if the value of the neutron reproduction factor $k > 1$.

For nuclei with mass number close to $119$ and $238$, the binding energies per nucleon are approximately $7.6 \text{ MeV}$ and $8.6 \text{ MeV}$ respectively. If a nucleus of mass number $238$ breaks into two nuclei of nearly equal masses, what will be the approximate amount of energy released in the process of fission (in $\text{ MeV}$)?

The process that mainly takes place in stars to produce energy is:

Assertion: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
Reason: For heavy nuclei,binding energy per nucleon increases with increasing $Z$,while for light nuclei,it decreases with increasing $Z$.

If $200 \text{ MeV}$ of energy is released in the fission of one nucleus of ${ }_{92}^{236} U$, the number of nuclei that must undergo fission to release an energy of $1000 \text{ J}$ is