A Recovery Point Objective (RPO) of zero means that the system is designed with high availability and fault tolerance in mind, ensuring that no transaction data is lost in the event of a system failure. This implies the use of real-time replication techniques, making it the most suitable option for the company's high-value transaction system. An RPO of 1 hour would mean accepting up to one hour of data loss, which isn't ideal for the high-value transactions. An RPO of 24 hours would suggest a much larger potential data loss window, which is not acceptable for this scenario. Lastly, increasing backup frequency could help reduce the amount of data lost, but it is not as effective as aiming for an RPO of zero, where data loss is nonexistent.