What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, y will play tennis if and only if y is a server. There is at least one y for which y is a server if and only if y will play tennis.
For all y, if y plays tennis, then y is a server. There is at least one y for which if y were a server, then y is playing tennis. For all y, if y were a server, then y is playing tennis. There is at least one y for which if y plays tennis, then y is a server.