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: If Joseph listens to a song, then Charles is making tea. If Joseph climbs a mountain, then Charles is making tea. It is cloudy if and only if Charles is making tea. For all x_17, x_17 will climb a mountain or x_17 will listen to a song.
If it is cloudy, then Charles is making tea can be inferred via the biconditional elimination rule. If Charles makes tea, then it is cloudy can be inferred via the biconditional elimination rule.