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 it is cloudy, then David is working. David is drinking water or it is cloudy. For all z, z will work if and only if z will drink water.
For all z, if z works, then z is drinking water can be inferred via the universal biconditional elimination rule. For all z, if z drinks water, then z is working can be inferred via the universal biconditional elimination rule.