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_2, if x_2 were curious, then x_2 is a nurse. For all x_2, if x_2 writes a letter, then x_2 is curious. For all x_2, if x_2 were a nurse, then x_2 is writing a letter.
For all x_2, if x_2 were curious, then x_2 is writing a letter can be inferred via the universal transitivity rule. For all x_2, if x_2 writes a letter, then x_2 is a nurse can be inferred via the universal transitivity rule. For all x_2, if x_2 were a nurse, then x_2 is curious can be inferred via the universal transitivity rule.