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: There is at least one x_12 for which if x_12 were a scientist, then x_12 is drinking water. For all x_12, if x_12 drinks water, then x_12 is a writer. For all x_12, if x_12 were a writer, then x_12 is drinking water. For all x_12, x_12 is a writer or x_12 is a scientist. For all x_12, if x_12 drinks water, then x_12 is a scientist.
For all x_12, if x_12 were a writer, then x_12 is a scientist can be inferred via the universal transitivity rule. There is at least one x_12 for which if x_12 were a scientist, then x_12 is a writer can be inferred via the existential transitivity rule. There is at least one x_12 for which x_12 will drink water can be inferred via the existential disjunction elimination rule. For all x_12, x_12 will drink water if and only if x_12 is a writer can be inferred via the universal biconditional introduction rule. For all x_12, x_12 is a writer if and only if x_12 will drink water can be inferred via the universal biconditional introduction rule. There is at least one x_12 for which x_12 is a scientist if and only if x_12 will drink water can be inferred via the existential biconditional introduction rule. There is at least one x_12 for which x_12 will drink water if and only if x_12 is a scientist can be inferred via the existential biconditional introduction rule.