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_13, if x_13 were an office clerk, then x_13 is a bartender. For all x_13, if x_13 listens to a song, then x_13 is playing squash. For all x_13, if x_13 climbs a mountain, then x_13 is a doctor. For all x_13, x_13 will climb a mountain or x_13 will listen to a song. For all x_13, x_13 is an office clerk. For all x_13, x_13 is not a doctor.
For all x_13, x_13 is a bartender can be inferred via the universal modus ponens rule. For all x_13, x_13 will not climb a mountain can be inferred via the universal modus tollens rule.