What best describes the term "High Availability" in system design?

High Availability (HA) in system design is primarily concerned with ensuring that a service or application remains operational and accessible to users, even in the face of failures. This is accomplished through implementing fault tolerance, which means that if one component of the system fails, there are mechanisms in place to maintain service continuity. For instance, by using redundant systems or failover strategies, organizations can reduce the risk of downtime and guarantee that users can access services seamlessly.

In cloud environments, this can involve using multiple availability zones, load balancing, and automated recovery processes to keep services running. Therefore, the focus of High Availability is not just on keeping systems up and running but also on ensuring that users experience minimal disruption regardless of hardware or software failures. This aligns perfectly with the definition provided in the correct answer.