What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z_2, if z_2 drives a car, then z_2 is listening to a song. For all z_2, if z_2 listens to a song, then z_2 is driving a car. There is at least one z_2 for which z_2 is sad if and only if z_2 will drive a car.
For all z_2, z_2 will drive a car if and only if z_2 will listen to a song. For all z_2, z_2 will listen to a song if and only if z_2 will drive a car. There is at least one z_2 for which if z_2 were sad, then z_2 is driving a car. There is at least one z_2 for which if z_2 drives a car, then z_2 is sad.