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_2 for which if x_2 were an astronaut, then x_2 is making tea. For all x_2, if x_2 were a doctor, then x_2 is making tea. For all x_2, x_2 is an astronaut or x_2 is a doctor. For all x_2, x_2 will make tea if and only if x_2 is a taxi driver.
There is at least one x_2 for which x_2 will make tea can be inferred via the existential disjunction elimination rule. For all x_2, if x_2 makes tea, then x_2 is a taxi driver can be inferred via the universal biconditional elimination rule. For all x_2, if x_2 were a taxi driver, then x_2 is making tea can be inferred via the universal biconditional elimination rule.