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: There is at least one x_4 for which x_4 will go running. For all x_4, if x_4 goes running, then x_4 is climbing a mountain. For all x_4, if x_4 climbs a mountain, then x_4 is reading a book. For all x_4, if x_4 were an office clerk, then x_4 is reading a book.
There is at least one x_4 for which x_4 will climb a mountain can be inferred via the existential modus ponens rule. For all x_4, if x_4 goes running, then x_4 is reading a book can be inferred via the universal transitivity rule.