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_5, x_5 is a nurse or x_5 will play a game. For all x_5, if x_5 were a nurse, then x_5 is a scientist. For all x_5, x_5 is not a scientist. For all x_5, x_5 is a mechanic.
For all x_5, x_5 is not a nurse can be inferred via the universal modus tollens rule.