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_4, x_4 will drive a car. For all x_4, x_4 will take a plane. For all x_4, if x_4 drives a car, then x_4 is climbing a mountain. For all x_4, if x_4 climbs a mountain, then x_4 is a police officer.
For all x_4, x_4 will climb a mountain can be inferred via the universal modus ponens rule. For all x_4, if x_4 drives a car, then x_4 is a police officer can be inferred via the universal transitivity rule. For all x_4, x_4 will drive a car and x_4 will take a plane can be inferred via the universal conjunction rule. For all x_4, x_4 will take a plane and x_4 will drive a car can be inferred via the universal conjunction rule.