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: Joseph is not reading a book. For all x_2, if x_2 reads a book, then x_2 is an office clerk. For all x_2, if x_2 were an office clerk, then x_2 is reading a book. For all x_2, if x_2 were an office clerk, then x_2 is reading a book.
For all x_2, x_2 will read a book if and only if x_2 is an office clerk can be inferred via the universal biconditional introduction rule. For all x_2, x_2 will read a book if and only if x_2 is an office clerk can be inferred via the universal biconditional introduction rule. For all x_2, x_2 is an office clerk if and only if x_2 will read a book can be inferred via the universal biconditional introduction rule. For all x_2, x_2 is an office clerk if and only if x_2 will read a book can be inferred via the universal biconditional introduction rule.