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: William is not making tea. Barbara is an office clerk. For all x_12, x_12 will make tea or x_12 will listen to a song. If Richard plays tennis, then Barbara is not an office clerk.
Richard is not playing tennis can be inferred via the modus tollens rule. William is not making tea and Barbara is an office clerk can be inferred via the conjunction rule. Barbara is an office clerk and William is not making tea can be inferred via the conjunction rule.