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 x_8, x_8 will climb a mountain or x_8 will make tea. For all x_8, x_8 is not a server. There is at least one x_8 for which x_8 will not climb a mountain or x_8 will cook. For all x_8, x_8 will make tea if and only if x_8 is a taxi driver. For all x_8, if x_8 were a taxi driver, then x_8 is a server.
For all x_8, x_8 is not a taxi driver can be inferred via the universal modus tollens rule. There is at least one x_8 for which x_8 will make tea or x_8 will cook can be inferred via the existential resolution rule. For all x_8, if x_8 makes tea, then x_8 is a taxi driver can be inferred via the universal biconditional elimination rule. For all x_8, if x_8 were a taxi driver, then x_8 is making tea can be inferred via the universal biconditional elimination rule.