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_8, if x_8 takes a plane, then x_8 is drinking water. There is at least one x_8 for which if x_8 writes a letter, then x_8 is taking a plane. For all x_8, if x_8 drinks water, then x_8 is writing a letter. For all x_8, x_8 will play squash. For all x_8, if x_8 drinks water, then x_8 is not playing squash.
For all x_8, x_8 will not drink water can be inferred via the universal modus tollens rule. For all x_8, if x_8 takes a plane, then x_8 is writing a letter can be inferred via the universal transitivity rule. There is at least one x_8 for which if x_8 writes a letter, then x_8 is drinking water can be inferred via the existential transitivity rule. There is at least one x_8 for which if x_8 drinks water, then x_8 is taking a plane can be inferred via the existential transitivity rule.