Consider a deployment of single$-$instance Paxos with five acceptors. A state is valid if there is some sequence of message deliveries and message drops and node failures that leads to the state, assuming a correct implementation of proposers and acceptors.

For each part, we give you the highest accepted proposal at all five acceptors: A$,$ B$,$ C$,$ D$,$ E at a single instance in time. Each acceptor$$s highest accepted proposal is either nil $($if it hasn$$t accepted any proposal$)$ or $($n$,$ v$)$ where n is the proposal number and v is a value.