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_1, if x_1 works, then x_1 is a doctor. Sarah is working if and only if Jessica is making tea. For all x_1, if x_1 were a doctor, then x_1 is working. For all x_1, x_1 is not a doctor.
If Sarah works, then Jessica is making tea can be inferred via the biconditional elimination rule. If Jessica makes tea, then Sarah is working can be inferred via the biconditional elimination rule. For all x_1, x_1 will not work can be inferred via the universal modus tollens rule. For all x_1, x_1 will work if and only if x_1 is a doctor can be inferred via the universal biconditional introduction rule. For all x_1, x_1 is a doctor if and only if x_1 will work can be inferred via the universal biconditional introduction rule.