In the context of disaster recovery, the Recovery Point Objective (RPO) is best defined by option B: The acceptable data loss measured in time that can be tolerated. RPO is a critical metric in disaster recovery and business continuity planning that specifies the maximum amount of data (measured in time) that an organization can afford to lose in the event of a disaster or system failure. It effectively sets the limit for how frequently data backups or replications should occur. For instance, an RPO of 4 hours means that the organization must be able to recover data from no more than 4 hours prior to the disaster, implying that backup or replication operations should occur at least every 4 hours. Establishing an RPO is essential for developing an effective data protection strategy, as it guides the choice of backup methodologies and technologies to meet the organization's tolerance for data loss.