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_1, if x_1 reads a book, then x_1 is a server. For all x_1, x_1 will read a book. For all x_1, if x_1 were happy, then x_1 is a server.
For all x_1, x_1 is a server can be inferred via the universal modus ponens rule.