Assertion: $P{u^{238}}$ is artificial nuclear fuel.
Reason: ${U^{238}}$ is a fertile material
A. Both assertion and reason are true and reason is the correct explanation of assertion.
B. Both assertion and reason are true but reason is not the correct explanation of assertion.
C. Assertion is true but reason is false.
D. Assertion is false but reason is true.
E. Both assertion and reason are false.

Hint: Nuclear fusion is a nuclear reaction in which two or more lighter nuclei are smashed together to react, and form one or more heavy atomic nuclei or subatomic particles such as neutrons and protons.

Complete step by step answer: $P{u^{238}}$is Plutonium- ${\text{239}}$, and ${U^{238}}$ is Uranium - ${\text{238}}$. The number ${\text{238 and 239}}$ tells about the mass numbers which is the sum number of protons and neutrons. Larger nuclei which have even atomic mass are generally fertile which means they can be used to make a fissile material upon absorption of neutrons. Since, ${U^{238}}$ has even atomic mass, so it can be a fertile material. When a neutron is introduced to a ${U^{238}}$ molecule, the neutron is absorbed by it to form a heavier nucleus of ${U^{239}}$. This ${U^{239}}$ is a radioactive beta-minus particle. So, it undergoes beta decay to form different nuclei called Neptunium - ${\text{239}}$. But Neptunium - ${\text{239}}$ is itself an unstable compound, so, it again goes beta decay to form stable $P{u^{238}}$ ( Plutonium- ${\text{238}}$).
So, both assertion and reason are true and reason is the correct explanation of the assertion.
So, the correct answer is “Option A”.

Note: The reaction occurring in the sun is similar to nuclear fusion where two hydrogen atoms collide and fuse together to form helium atoms. The reaction would be: ${}_1^2H + {}_1^3H \to {}_2^4He + {}_0^1n$. The fusion reaction is highly exothermic, that’s why the Sun has a vast amount of heat energy.