Final answer:
The correct option is D). The industry standard for high availability often referred to is 'Five 9s' (99.999% uptime), indicates that a system is expected to be down for no more than 5.26 minutes per year.
Step-by-step explanation:
The question you're asking relates to the measure of system reliability in the context of uptime and availability within the field of information technology and computing. When we talk about system availability, we are referring to the percentage of time a system is operational and accessible to users within a given period. The phrases 'Five 9s', 'Six 9s', and so on, describe the percentage of uptime of a service. Specifically, 'Five 9s' corresponds to 99.999% uptime, 'Six 9s' to 99.9999% uptime, and so forth.
Among the choices given, Five 9s (99.999% uptime) is a widely recognized industry target for high availability. It implies that the system is down for no more than 5.26 minutes per year. While there are more ambitious targets, such as 'Six 9s' or 'Seven 9s', they are much harder to achieve and are not as commonly expected as the standard of Five 9s in most industries. Therefore, the correct answer to which is an industry-standard for high availability is Five 9s (Option D).