What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_3, if x_3 were an office clerk, then x_3 is taking a plane. For all x_3, if x_3 were an office clerk, then x_3 is taking a plane. There is at least one x_3 for which if x_3 takes a plane, then x_3 is an office clerk.
There is at least one x_3 for which x_3 will take a plane if and only if x_3 is an office clerk. There is at least one x_3 for which x_3 will take a plane if and only if x_3 is an office clerk. There is at least one x_3 for which x_3 is an office clerk if and only if x_3 will take a plane. There is at least one x_3 for which x_3 is an office clerk if and only if x_3 will take a plane.