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_1 for which x_1 is a taxi driver. For all x_1, x_1 will play tennis. For all x_1, if x_1 plays tennis, then x_1 is listening to a song.
For all x_1, x_1 will listen to a song can be inferred via the universal modus ponens rule. There is at least one x_1 for which x_1 is a taxi driver and x_1 will play tennis can be inferred via the existential conjunction rule. There is at least one x_1 for which x_1 will play tennis and x_1 is a taxi driver can be inferred via the existential conjunction rule.