Answer: Correct answer is Radioactive Isotopes.
The most significant waste products of nuclear energy is RADIOACTIVE ISOTOPES.
Radioactive isotopes waste are waste products containing hazardous radioactive materials that are harmful to humans, animals and the environment.
Although radioactivity decreases over time so these types of waste are stored in the appropriate facility to make them less harmful before being released to the environment. All radioactive waste disposal are being regulated by the government.