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_18 for which if x_18 were bored, then x_18 is a nurse. For all x_18, x_18 is bored or x_18 is an office clerk. For all x_18, x_18 will not play tennis. For all x_18, if x_18 were a nurse, then x_18 is playing tennis.
For all x_18, x_18 is not a nurse can be inferred via the universal modus tollens rule. There is at least one x_18 for which if x_18 were bored, then x_18 is playing tennis can be inferred via the existential transitivity rule.