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: For all x_9, x_9 is a janitor. For all x_9, x_9 will listen to a song or x_9 is an astronaut. For all x_9, x_9 is an electrician. For all x_9, if x_9 listens to a song, then x_9 is not a janitor.
For all x_9, x_9 will not listen to a song can be inferred via the universal modus tollens rule. For all x_9, x_9 is a janitor and x_9 is an electrician can be inferred via the universal conjunction rule. For all x_9, x_9 is an electrician and x_9 is a janitor can be inferred via the universal conjunction rule.