(N/A) No source of energy can be considered truly pollution-free.
While some sources like solar cells are often labeled as pollution-free,their manufacturing process causes indirect environmental damage.
Similarly,in the case of nuclear fusion,although the fusion reaction itself does not produce radioactive waste,the process requires an extremely high temperature of approximately $10^7\, K$.
This temperature is typically achieved through nuclear fission reactions,which generate highly hazardous radioactive waste.
Therefore,considering the entire lifecycle and the processes involved,no source of energy is completely pollution-free.