What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z, z will work or z is happy. For all z, z is not happy or z will write a letter. There is at least one z for which z will not work or z will drive a car. For all z, z will not drive a car.
There is at least one z for which z is happy or z will drive a car.