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_5, if x_5 listens to a song, then x_5 is playing tennis. For all x_5, if x_5 plays tennis, then x_5 is a sailor. For all x_5, x_5 will not write a letter. For all x_5, if x_5 were a sailor, then x_5 is writing a letter.
For all x_5, x_5 is not a sailor can be inferred via the universal modus tollens rule. For all x_5, if x_5 listens to a song, then x_5 is a sailor can be inferred via the universal transitivity rule. For all x_5, if x_5 plays tennis, then x_5 is writing a letter can be inferred via the universal transitivity rule.