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_3, x_3 will read a book or x_3 will take a plane. For all x_3, x_3 will take a plane if and only if x_3 is a police officer. For all x_3, if x_3 reads a book, then x_3 is a police officer.
For all x_3, if x_3 takes a plane, then x_3 is a police officer can be inferred via the universal biconditional elimination rule. For all x_3, if x_3 were a police officer, then x_3 is taking a plane can be inferred via the universal biconditional elimination rule.