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 will make tea if and only if z is a server. For all z, z is not rich. For all z, if z were a server, then z is rich. For all z, if z makes tea, then z is a server.
For all z, z is not a server can be inferred via the universal modus tollens rule. For all z, if z makes tea, then z is rich can be inferred via the universal transitivity rule. For all z, if z makes tea, then z is a server can be inferred via the universal biconditional elimination rule. For all z, if z were a server, then z is making tea can be inferred via the universal biconditional elimination rule.