Question: In the context of UTRAN network resources, what is the condition for the presence of the ExternalUtranNeighbourCellRelation role in a particular UtranRelation?
Option 1: The UtranNeighbourCellRelation of the same UtranRelation is also present.
Option 2: The UtranGenericCell has an established connection with the UtranRelation.
Option 3: The UtranNeighbourCellRelation of this particular UtranRelation is absent.
Option 4: A new cell is added to the UTRAN network, updating all relations.
Explanation: According to the defined roles for the ExternalUtranNeighbourCellRelation, this role must be present if (and only if) the UtranNeighbourCellRelation of the same particular UtranRelation is absent. This ensures a mutually exclusive relationship between these two roles within any given UtranRelation, likely designed to maintain consistency and clarity in network resource management.