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_12, if x_12 climbs a mountain, then x_12 is a taxi driver. For all x_12, x_12 will make tea. For all x_12, x_12 is not an astronaut. For all x_12, x_12 is an astronaut if and only if x_12 is a nurse. For all x_12, x_12 is a nurse or x_12 will climb a mountain.
For all x_12, if x_12 were an astronaut, then x_12 is a nurse can be inferred via the universal biconditional elimination rule. For all x_12, if x_12 were a nurse, then x_12 is an astronaut can be inferred via the universal biconditional elimination rule. For all x_12, x_12 is not a nurse can be inferred via the universal biconditional elimination rule.