Balancing a$.$ ensures that the input and output data flows of the child data flow diagram $($DFD$)$ are maintained on the parent data flow diagram $($DFD$)$ b$.$ uses a series of increasingly sketchy data flow diagrams $($DFDs$)$ to describe an information system c$.$ ensures that the input and output data flows of the parent data flow diagram $($DFD$)$ are maintained on the child data flow diagram $($DFD$)$ d$.$ uses a serles of increasingly detailed data flow diagrams $($DFDs$)$ to describe an information system