Single version of the truth means that everyone has access to the same information and it is always the same. It is a way to make sure that everyone has the correct information and it's not wrong, or different for different people. It's like when you tell your mom something and then tell your dad the same thing. You want to make sure the information is the same, so that everyone knows the same thing. Single version of the truth helps everyone have the same understanding of what is going on and makes things easier to work together.