In a nuclear reactor, one of the following is used as a fuel. A. Coal B. Uranium C. Radium D. Diesel

The correct answer is B. Uranium.

Uranium is a radioactive metal that is used as a fuel in nuclear reactors. When uranium atoms are split, they release a large amount of energy. This energy is used to heat water, which turns into steam. The steam then drives a turbine, which generates electricity.

Coal is a fossil fuel that is used to generate electricity. Coal is not a nuclear fuel.

Radium is a radioactive metal that is used in some medical treatments. Radium is not a nuclear fuel.

Diesel is a type of fuel that is used in diesel engines. Diesel is not a nuclear fuel.