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_3, x_3 is a writer or x_3 will read a book. For all x_3, if x_3 sleeps, then x_3 is sad. There is at least one x_3 for which if x_3 reads a book, then x_3 is drinking water. For all x_3, if x_3 drinks water, then x_3 is sad. For all x_3, x_3 is not a writer or x_3 will sleep.
There is at least one x_3 for which if x_3 reads a book, then x_3 is sad can be inferred via the existential transitivity rule. For all x_3, x_3 will read a book or x_3 will sleep can be inferred via the universal resolution rule.