Read the passage. I was waiting in line at the department store return counter. I got more and more frustrated. Calls were constantly being taken by the clerk on her cell phone.

Which option shows the best way to revise the passage for clarity and cohesion?

As I waited in line at the department store’s return counter, I became more and more frustrated because the clerk was constantly taking calls on her cell phone.
I was waiting in line at the department store return counter, and I got more and more frustrated; calls were constantly being taken by the clerk on her cell phone.
While I waited in line at the department store return counter. I got more and more frustrated; the clerk was constantly taking calls on her cell phone.
I was waiting in line at the department store return counter, so I got more and more frustrated. Calls were constantly being taken by the clerk on her cell phone.