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: If Patricia were a writer, then it is sunny. If it is sunny, then Patricia is listening to a song. For all x_15, if x_15 were a writer, then x_15 is listening to a song. For all x_15, if x_15 listens to a song, then x_15 is a writer.
If Patricia were a writer, then Patricia is listening to a song can be inferred via the transitivity rule. For all x_15, x_15 is a writer if and only if x_15 will listen to a song can be inferred via the universal biconditional introduction rule. For all x_15, x_15 will listen to a song if and only if x_15 is a writer can be inferred via the universal biconditional introduction rule.