What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 drinks water, then x_4 is a nurse. For all x_4, x_4 is a taxi driver or x_4 will drink water. For all x_4, x_4 is a politician. For all x_4, if x_4 were a taxi driver, then x_4 is a nurse.
For all x_4, x_4 is a nurse.