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_7, x_7 is not an office clerk. For all x_7, x_7 will make tea if and only if x_7 is an office clerk. For all x_7, x_7 will make tea if and only if x_7 is a nurse.
For all x_7, if x_7 makes tea, then x_7 is an office clerk can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 makes tea, then x_7 is a nurse can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were an office clerk, then x_7 is making tea can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 were a nurse, then x_7 is making tea can be inferred via the universal biconditional elimination rule. For all x_7, x_7 will not make tea can be inferred via the universal biconditional elimination rule.