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