What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_9, if x_9 sleeps, then x_9 is listening to a song. For all x_9, if x_9 were a police officer, then x_9 is listening to a song. There is at least one x_9 for which x_9 is a police officer or x_9 will sleep. For all x_9, if x_9 writes a letter, then x_9 is not listening to a song.
There is at least one x_9 for which x_9 will listen to a song.