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, x_1 will write a letter. For all x_1, if x_1 writes a letter, then x_1 is drinking water. For all x_1, if x_1 were a writer, then x_1 is drinking water.
For all x_1, x_1 will drink water can be inferred via the universal modus ponens rule.