Magnets are created due to the uniform motion of a) electrons. b) iron. c) metal. d) nuclei.

The correct answer is option A, electron

Reason -

Magnetism is caused due to the electric charge (electron) motion. When an electric charge moves , a magnetic effect is produced at right angle to its direction of motion.  

For instance if we place a steel or iron nail inside a coil through which electricity is passed at right angle , the nail gets converted to magnet.  

its temperature is increasing. this causes molecular vibrations to increase.