What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Richard makes tea, then Susan is cooking. If Susan cooks, then Richard is making tea. Richard is making tea. Barbara is a soldier.
Susan is cooking. Richard is making tea and Barbara is a soldier. Barbara is a soldier and Richard is making tea. Richard is making tea if and only if Susan is cooking. Susan is cooking if and only if Richard is making tea.