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_10, x_10 will play tennis if and only if x_10 will climb a mountain. There is at least one x_10 for which if x_10 plays tennis, then x_10 is a carpenter. For all x_10, x_10 is an electrician. For all x_10, if x_10 were a carpenter, then x_10 is not an electrician.
For all x_10, x_10 is not a carpenter can be inferred via the universal modus tollens rule. For all x_10, if x_10 plays tennis, then x_10 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 climbs a mountain, then x_10 is playing tennis can be inferred via the universal biconditional elimination rule.