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_2, x_2 is a sailor if and only if x_2 is an office clerk. For all x_2, if x_2 were an office clerk, then x_2 is a sailor. Linda is not an office clerk. If it snows, then Linda is a sailor.
For all x_2, if x_2 were a sailor, then x_2 is an office clerk can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 were an office clerk, then x_2 is a sailor can be inferred via the universal biconditional elimination rule.