A. The new message replaces the first message only for users who no longer exist in the audience

B. The new message replaces the first message for every user who received the first message, regardless if they still exist in the audience or not

C. The new message replaces the first message, and for users who no longer exist in the audience, the first message is deleted from the user's inbox

D. All users receive the new message, but only if they're read the first message