Answer: The adverb slowly describes the verb walked. It basically says HOW the person walks (like did they walk fast, slow, at an average pace, etc., and in this case, it says that they walked in a slow manner).
Edit: so I’m assuming effect is like the mood of the story created, and I’d say that it creates a somber, suspenseful feeling, opposed to if she was walking quickly, which would create a rushed mood.
A sounds like the most likely answer, since it shows that she cares for him and wants to do something special for him.
They were invaded......................
She’s wondering about what is the moral proper thing to do