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_10, if x_10 climbs a mountain, then x_10 is a police officer. Barbara is a sailor if and only if Elisabeth is a police officer. Barbara is a sailor or Elisabeth is climbing a mountain.
If Elisabeth makes tea, then Barbara is a sailor can be inferred via the rewriting rule. If Barbara were a sailor, then Elisabeth is a police officer can be inferred via the biconditional elimination rule. If Elisabeth were a police officer, then Barbara is a sailor can be inferred via the biconditional elimination rule.