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 will listen to a song if and only if x_8 is a police officer. There is at least one x_8 for which x_8 is not a police officer. For all x_8, x_8 will listen to a song if and only if x_8 will make tea.
For all x_8, if x_8 listens to a song, then x_8 is a police officer can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 listens to a song, then x_8 is making tea can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a police officer, then x_8 is listening to a song can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 makes tea, then x_8 is listening to a song can be inferred via the universal biconditional elimination rule. There is at least one x_8 for which x_8 will not listen to a song can be inferred via the existential biconditional elimination rule.