What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, y is a doctor or y is not an office clerk. For all y, if y were a doctor, then y is an office clerk. There is at least one y for which y is not an office clerk. For all y, if y were an office clerk, then y is a doctor.
There is at least one y for which y is not a doctor. For all y, if y were an office clerk, then y is a doctor. For all y, y is a doctor if and only if y is an office clerk. For all y, y is an office clerk if and only if y is a doctor.