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_10, x_10 will sleep or x_10 is a scientist. If Linda sleeps, then Sarah is taking a plane. If Sarah takes a plane, then Linda is sleeping. Sarah is not taking a plane.
Linda is not sleeping can be inferred via the modus tollens rule.