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_8, x_8 is a janitor. For all x_8, if x_8 listens to a song, then x_8 is a poet. For all x_8, if x_8 listens to a song, then x_8 is not a janitor. For all x_8, x_8 is a poet if and only if x_8 will listen to a song.
For all x_8, x_8 will not listen to a song can be inferred via the universal modus tollens rule. For all x_8, if x_8 were a poet, then x_8 is listening to a song can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 listens to a song, then x_8 is a poet can be inferred via the universal biconditional elimination rule.