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, if z drives a car, then z is an astronaut. For all z, if z were an astronaut, then z is driving a car. For all z, if z drives a car, then z is an astronaut.
For all z, z will drive a car if and only if z is an astronaut can be inferred via the universal biconditional introduction rule. For all z, z is an astronaut if and only if z will drive a car can be inferred via the universal biconditional introduction rule. For all z, z is an astronaut if and only if z will drive a car can be inferred via the universal biconditional introduction rule. For all z, z will drive a car if and only if z is an astronaut can be inferred via the universal biconditional introduction rule.