High Availability (HA) and Disaster Recovery (DR) serve different purposes in a system's architecture, although they both contribute to the system's overall reliability.
High Availability is about ensuring that a system remains operational and accessible as much as possible, even in the event of a failure of part of the system. This is achieved through redundancy and failover mechanisms. If a component fails, the system can automatically switch to a backup component. This provides a continuous user experience, which is what the question is asking for.
Disaster Recovery, on the other hand, is about restoring a system after a major incident or disaster that causes a significant system outage. This could involve restoring from backups, switching to a disaster recovery site, etc. This process may not be immediate and could result in some downtime.
So, in the context of providing a continuous user experience in the event of a resource failure, High Availability is the correct answer.