What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If David reads a book, then Sarah is taking a plane. For all x_13, if x_13 takes a plane, then x_13 is writing a letter. If Jennifer were bored, then Sarah is writing a letter. Robert is climbing a mountain or Jennifer is bored. Robert is not climbing a mountain or David is reading a book.
Jennifer is bored or David is reading a book.