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_6, if x_6 plays tennis, then x_6 is drinking water. For all x_6, x_6 will not climb a mountain. For all x_6, if x_6 climbs a mountain, then x_6 is playing tennis. For all x_6, if x_6 plays tennis, then x_6 is climbing a mountain. For all x_6, if x_6 drinks water, then x_6 is playing tennis.
For all x_6, x_6 will not play tennis can be inferred via the universal modus tollens rule. For all x_6, if x_6 climbs a mountain, then x_6 is drinking water can be inferred via the universal transitivity rule. For all x_6, if x_6 drinks water, then x_6 is climbing a mountain can be inferred via the universal transitivity rule. For all x_6, x_6 will play tennis if and only if x_6 will drink water can be inferred via the universal biconditional introduction rule. For all x_6, x_6 will climb a mountain if and only if x_6 will play tennis can be inferred via the universal biconditional introduction rule. For all x_6, x_6 will play tennis if and only if x_6 will climb a mountain can be inferred via the universal biconditional introduction rule. For all x_6, x_6 will drink water if and only if x_6 will play tennis can be inferred via the universal biconditional introduction rule.