Answer : The correct option is,
![A\rightarrow B+C+n](https://img.qammunity.org/2020/formulas/chemistry/college/cau3m7la4ies9x88qijexakecarc1lyu72.png)
Explanation :
Nuclear fusion : It is a process where the two small nuclei converted to form a heavy nuclei and release some energy.
Nuclear fission : It is a process where a heavier nuclei (unstable nuclei) converted into two or more small (stable nuclei) and release some energy.
From the given reactions, we conclude that the reaction that shows the nuclear fission reaction is:
![A\rightarrow B+C+n](https://img.qammunity.org/2020/formulas/chemistry/college/cau3m7la4ies9x88qijexakecarc1lyu72.png)
Hence, the nuclear fission reaction is,
![A\rightarrow B+C+n](https://img.qammunity.org/2020/formulas/chemistry/college/cau3m7la4ies9x88qijexakecarc1lyu72.png)