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 working. For all x_6, if x_6 works, then x_6 is an office clerk. For all x_6, x_6 will not play tennis. For all x_6, if x_6 were an office clerk, then x_6 is playing tennis.
For all x_6, x_6 is not an office clerk can be inferred via the universal modus tollens rule. For all x_6, if x_6 plays tennis, then x_6 is an office clerk can be inferred via the universal transitivity rule. For all x_6, if x_6 works, then x_6 is playing tennis can be inferred via the universal transitivity rule. For all x_6, if x_6 were an office clerk, then x_6 is working can be inferred via the universal transitivity rule.