As the title says, I'm confused about subject/topic markers. So I have a few questions about how they are used.
Q1. Why is 출구는 used for A1, A3-5, but 출구가 is used for A2?
A: (1)“Where should I go to ...
Question and answer:
1.백화점에 사람 아주 많았습니다.
2.백화점은 사람 아주 많았습니다.
The question and the answer #1 is from a Korean textbook (not written by a native Korean). I am not sure if the answer #2 is ...