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: exists x_4: T(x_4) -> Q(x_4). forall x_4: Q(x_4) -> T(x_4). forall x_4: T(x_4) -> Q(x_4).
forall x_4: Q(x_4) <-> T(x_4) can be inferred via the universal biconditional introduction rule. forall x_4: T(x_4) <-> Q(x_4) can be inferred via the universal biconditional introduction rule. exists x_4: T(x_4) <-> Q(x_4) can be inferred via the existential biconditional introduction rule. exists x_4: Q(x_4) <-> T(x_4) can be inferred via the existential biconditional introduction rule.