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 climbs a mountain, then x_1 is curious. For all x_1, x_1 is not an artist. For all x_1, x_1 is an artist if and only if x_1 will climb a mountain. For all x_1, if x_1 were curious, then x_1 is sad. For all x_1, if x_1 were sad, then x_1 is climbing a mountain.
For all x_1, if x_1 climbs a mountain, then x_1 is sad can be inferred via the universal transitivity rule. For all x_1, if x_1 were curious, then x_1 is climbing a mountain can be inferred via the universal transitivity rule. For all x_1, if x_1 were sad, then x_1 is curious can be inferred via the universal transitivity rule. For all x_1, if x_1 were an artist, then x_1 is climbing a mountain can be inferred via the universal biconditional elimination rule. For all x_1, if x_1 climbs a mountain, then x_1 is an artist can be inferred via the universal biconditional elimination rule. For all x_1, x_1 will not climb a mountain can be inferred via the universal biconditional elimination rule.