What rule concerning the conch is made?

After Ralph, Simon, and Roger return from their expedition around the island, Ralph calls an assembly and addresses the group of boys. Ralph begins by mentioning that they are on an uninhabited island and will need to look after themselves. Ralph then tells the boys that they cannot have everyone speaking at once during the assemblies. He proceeds to create a rule regarding the conch, which states that anyone holding the conch during an assembly will have the platform to speak without being interrupted. Ralph likens the rule regarding the conch to "hands up" at school, where the speaker can address the group without interruptions or distractions.
The rule regarding the conch promotes democracy, as each boy, including the littluns, has a chance to speak and express their opinions during assemblies without being interrupted. Therefore, the conch becomes a powerful symbol of civilization and democracy on the island.