Answer:
It foreshadows Tom’s departure from his family at the end of the play.
Explanation:
By going out to the fire escape and smoking, Tom is choosing to distance himself from his mother and sister. His mother frowns upon his excessive smoking, and his sister is afraid for his safety and well-being when she sees he is constantly unhappy. His further alienation from them and the rest of the world by going to the movies continuously only solidifies this argument.
I also have taken a unit test on the book and got this one right, if that convinces you any more. Good day everyone!