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 will sleep or x_9 is a taxi driver. For all x_9, x_9 will not sleep. For all x_9, x_9 will listen to a song. For all x_9, if x_9 listens to a song, then x_9 is climbing a mountain.
For all x_9, x_9 will climb a mountain can be inferred via the universal modus ponens rule. For all x_9, x_9 is a taxi driver can be inferred via the universal disjunctive syllogism rule.