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, z is a sailor or z will write a letter. For all z, if z were a sailor, then z is a bartender. For all z, if z writes a letter, then z is a bartender.
For all z, z is a bartender can be inferred via the universal disjunction elimination rule.