An organization's critical application is required to be continuously available, with only a few minutes' per month of downtime allowed. what measure should the organization implement to assure this level of availability?

Availability is usually expressed as a percentage of uptime in a given year. SLAs often refer to monthly downtime or availability in order to calculate service credits to match monthly billing cycles. Many computing sites exclude scheduled downtime from availability calculations. By doing this, they can claim to have phenomenally high availability, But if the requirement is for true high availability, then downtime is downtime whether or not it is scheduled.