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: If Susan were rich, then David is a doctor. If David were a doctor, then James is not a sailor. James is a sailor. Jennifer is making tea.
David is not a doctor can be inferred via the modus tollens rule. James is a sailor and Jennifer is making tea can be inferred via the conjunction rule. Jennifer is making tea and James is a sailor can be inferred via the conjunction rule.