Which is the relationship between the clauses in this sentence: after leaving the gym, Angie made sure to stretch her legs. Is it a relationship between two independent clauses, a relationship between a dependent clause and an independent clause, a relationship within a single independent clause, or a relationship between a dependent clause and two independent clauses

The relationship between the clauses in the sentence "after leaving the gym, Angie made sure to stretch her legs" is a relationship between a dependent clause ("after leaving the gym") and an independent clause ("Angie made sure to stretch her legs").