When a parent and child team up against the second parent,this is an example of _______________.

A) lifecycle stage
B) subsystem
C) behavioral sequences
D) cross-generational coalition

A cross-generational coalition is a dynamic in which a parent and child ally against the other parent. This can be detrimental to the family system, as it disrupts the natural hierarchy and can lead to triangulation and other unhealthy patterns of communication. A lifecycle stage refers to a phase of the family life cycle (e.g. early childhood, adolescence, empty nest) and does not necessarily pertain to this specific situation. A subsystem refers to a smaller group within the family system (e.g. parent-child, siblings) and while it is relevant to this situation, it does not capture the unique dynamic of a cross-generational coalition. Behavioral sequences refer to the routines and patterns of interaction that occur within the family system, and again, while relevant, do not specifically address the situation of a parent and child teaming up against the other parent.