Final answer:
Matt and Sarah are in the attraction stage of relational development.
Step-by-step explanation:
Matt and Sarah are in the early stages of relational development, specifically the attraction stage.
At this stage, Matt finds Sarah physically attractive and intelligent based on her contributions in class. He is interested in getting to know her better. The attraction stage is characterized by initial impressions and a desire to pursue a relationship.
Matt's considerations about his next move indicate that he is in the early stages of building a relationship with Sarah.