Which of the following elements is non-radioactive ? A. Uranium B. Thorium C. Plutonium D. Zirconium

The correct answer is D. Zirconium.

Uranium, thorium, and plutonium are all radioactive elements. Zirconium is a non-radioactive element.

Uranium is a naturally occurring radioactive metal that is found in rocks and soil. It is used in nuclear power plants and nuclear weapons.

Thorium is a naturally occurring radioactive metal that is found in rocks and soil. It is used in some nuclear power plants.

Plutonium is a man-made radioactive metal that is used in nuclear weapons.

Zirconium is a non-radioactive metal that is used in a variety of applications, including jewelry, medical implants, and nuclear reactors.