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 z_4, if z_4 drives a car, then z_4 is a police officer. For all z_4, if z_4 were a doctor, then z_4 is driving a car.
For all z_4, if z_4 were a doctor, then z_4 is a police officer can be inferred via the universal transitivity rule.