What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x, x is happy or x is not sad. For all x, x is sad if and only if x is happy.
For all x, if x were sad, then x is happy. For all x, if x were sad, then x is happy. For all x, if x were happy, then x is sad.