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_2, z_2 will drive a car and z_2 will drink water. There is at least one z_2 for which if z_2 drives a car, then z_2 is working. For all z_2, if z_2 works, then z_2 is driving a car.
For all z_2, z_2 will drive a car can be inferred via the universal simplification rule. For all z_2, z_2 will drink water can be inferred via the universal simplification rule. There is at least one z_2 for which z_2 will drive a car if and only if z_2 will work can be inferred via the existential biconditional introduction rule. There is at least one z_2 for which z_2 will work if and only if z_2 will drive a car can be inferred via the existential biconditional introduction rule.