Billie and Tom Used to Have Occasional Conflicts in Their

Billie and Tom used to have occasional conflicts in their relationship.Five years later,they have grown apart.They still disagree occasionally,but they don't bother to argue about anything.This illustrates

A) that conflict is always bad.
B) that conflict can signify that people care about a relationship or situation.
C) that conflict always leads to estrangement.
D) that conflict can,over time,follow the biofeedback principle.