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: If Richard plays tennis, then Barbara is making tea. James is not climbing a mountain. James is climbing a mountain if and only if Richard is playing tennis. If Charles were a janitor, then Richard is playing tennis. If Barbara makes tea, then Charles is a janitor.
If Richard plays tennis, then Charles is a janitor can be inferred via the transitivity rule. If Charles were a janitor, then Barbara is making tea can be inferred via the transitivity rule. If Barbara makes tea, then Richard is playing tennis can be inferred via the transitivity rule. If James climbs a mountain, then Richard is playing tennis can be inferred via the biconditional elimination rule. If Richard plays tennis, then James is climbing a mountain can be inferred via the biconditional elimination rule. Richard is not playing tennis can be inferred via the biconditional elimination rule.