Final answer:
The stage of relational development where communication is typically brief and adheres to conventional formulas is known as the initiating stage. This is the phase where first impressions are made and basic, polite conversation occurs.
Step-by-step explanation:
In which stage of relational development is the communication usually brief and follows conventional formulas? The correct answer is a. initiating.
Dating back to Mark Knapp's model of relational development, the initiating stage is characterized by short, polite exchanges that follow societal norms. This is where individuals make first impressions and decide whether or not to pursue further interaction. At this stage, communication is often superficial, covering topics like the weather or current events, rather than personal information.