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_7, if x_7 were a police officer, then x_7 is playing squash. There is at least one x_7 for which if x_7 plays squash, then x_7 is taking a plane. For all x_7, if x_7 takes a plane, then x_7 is driving a car. For all x_7, if x_7 drinks water, then x_7 is a police officer.
For all x_7, if x_7 drinks water, then x_7 is playing squash can be inferred via the universal transitivity rule. There is at least one x_7 for which if x_7 plays squash, then x_7 is driving a car can be inferred via the existential transitivity rule. There is at least one x_7 for which if x_7 were a police officer, then x_7 is taking a plane can be inferred via the existential transitivity rule.