disaster recovery plan for a Lockheed Martin's accounting system specifies that the recovery point objective $($RPO$)$ is zero and the recovery time objective $($RTO$)$ is $72$ hours. Which of the following is the most cost$-$effective solution?

O Synchronous updates of the data and standby active systems in a hot site

$$ Synchronous remote copy of the data in a warm site that can be operational in $48$ hours

$$ A hot site that can be operational in eight hours with asynchronous backup of the transaction logs

O Distributed database systems in multiple locations updated asynchronously