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: Elisabeth is not driving a car. If Patricia were not a cashier, then it is windy. If Patricia were a cashier, then Jennifer is writing a letter. If Jennifer writes a letter, then Elisabeth is driving a car.
Jennifer is not writing a letter can be inferred via the modus tollens rule.