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_9, if x_9 plays squash, then x_9 is a police officer. For all x_9, x_9 will not drink water. There is at least one x_9 for which x_9 is a police officer if and only if x_9 will make tea. For all x_9, x_9 will drink water or x_9 will make tea.
For all x_9, x_9 will make tea can be inferred via the universal disjunctive syllogism rule. There is at least one x_9 for which if x_9 were a police officer, then x_9 is making tea can be inferred via the existential biconditional elimination rule. There is at least one x_9 for which if x_9 makes tea, then x_9 is a police officer can be inferred via the existential biconditional elimination rule.