The difference between fission and fusion is that ...

A. Fusion is the splitting of a nucleus

B. Fission is the joining of two nuclei

C. Fission is the splitting of a nucleus

D. There is not a difference

Fusion and fission are both nuclear reactions that produce energy, but fusion is two nucleus joining (think about fuse or fusing), while fission is a nucleus splitting (think about fissure)

so the correct answer is C. Fission is the splitting of a nucleus

Both fission and fusion are nuclear processes by which atoms are altered to create energy, but what is the difference between the two? Simply put, fission is the division of one atom into two, and fusion is the combination of two lighter atoms into a larger one. They are opposing processes, and therefore very different.