What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: There is at least one x_12 for which if x_12 works, then x_12 is listening to a song. For all x_12, x_12 will listen to a song if and only if x_12 is a police officer. For all x_12, x_12 will work or x_12 will not sleep.
For all x_12, if x_12 sleeps, then x_12 is working can be inferred via the universal rewriting rule. For all x_12, if x_12 listens to a song, then x_12 is a police officer can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a police officer, then x_12 is listening to a song can be inferred via the universal biconditional elimination rule.