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: There is at least one x_5 for which if x_5 were an office clerk, then x_5 is an artist. For all x_5, x_5 is a lawyer. For all x_5, if x_5 were a taxi driver, then x_5 is not a lawyer. For all x_5, if x_5 were an artist, then x_5 is a taxi driver.
For all x_5, x_5 is not a taxi driver can be inferred via the universal modus tollens rule. There is at least one x_5 for which if x_5 were an office clerk, then x_5 is a taxi driver can be inferred via the existential transitivity rule.