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_7, x_7 will climb a mountain or x_7 will take a plane. For all x_7, if x_7 climbs a mountain, then x_7 is running. There is at least one x_7 for which x_7 is a police officer. For all x_7, x_7 will take a plane if and only if x_7 will go running.
For all x_7, if x_7 takes a plane, then x_7 is running can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 goes running, then x_7 is taking a plane can be inferred via the universal biconditional elimination rule.