What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If William works, then Susan is a nurse. For all z_2, z_2 will work if and only if z_2 will cook.
For all z_2, if z_2 works, then z_2 is cooking. For all z_2, if z_2 cooks, then z_2 is working.