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_3, if x_3 drives a car, then x_3 is playing squash. For all x_3, if x_3 climbs a mountain, then x_3 is driving a car. There is at least one x_3 for which x_3 will climb a mountain.
There is at least one x_3 for which x_3 will drive a car can be inferred via the existential modus ponens rule. For all x_3, if x_3 climbs a mountain, then x_3 is playing squash can be inferred via the universal transitivity rule.