In a UML sequence diagram, what does a lifeline represent, and how is it typically depicted? Choose one 10 points A lifeline represents a message exchange between two objects and is depicted as a solid horizontal line. A lifeline represents the lifespan of an object and is depicted as a dashed vertical line. A lifeline represents the sequence of actions within an operation and is depicted as a dashed horizontal line. A lifeline represents the class diagram and is depicted as a solid vertical line