Read the following case and answer the question given below:
Riya wanted to find out which materials allow electric current to pass through them. She made a simple tester using an electric cell, a bulb, wires, and a switch. First, she touched the two free wire ends together and observed that the bulb glowed. Then, she tested different objects such as a coin, key, rubber piece, wooden block, aluminium foil, plastic scale, and pencil lead by placing them between the free wire ends. She noticed that the bulb glowed for some objects but did not glow for others. From this activity, she understood that some materials are conductors while others are insulators.
Which of the following objects from the case study are conductors of electricity?