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: There is at least one x_3 for which if x_3 climbs a mountain, then x_3 is bored. For all x_3, x_3 is bored if and only if x_3 will climb a mountain.
For all x_3, if x_3 were bored, then x_3 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_3, if x_3 climbs a mountain, then x_3 is bored can be inferred via the universal biconditional elimination rule.