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, if x_5 cooks, then x_5 is a nurse. For all x_5, x_5 is not a nurse. There is at least one x_5 for which if x_5 reads a book, then x_5 is not sad. For all x_5, x_5 will cook or x_5 is sad.
For all x_5, x_5 will not cook can be inferred via the universal modus tollens rule.