Touching the metal insides of a hot oven will likely burn your hands. However, if you hold your hand briefly in the hot air inside the oven you’ll be fine. What conclusion can you draw from these observations?

Both metal and air are good conductors of heat.

Metal is a good conductor of heat, but the air is a poor conductor of heat.

Air is a good conductor of heat, but metal is a poor conductor of heat.

Both metal and air are poor conductors of heat.