Final answer:
When a case initially set to normal priority at 16:00 is changed to critical at 16:15, there are 15 minutes left before the SLA fails, as the SLA warning is at 15 minutes and failure at 30 minutes after it becomes critical. Therefore, it will fail at 16:30, which is 15 minutes after the priority change.
Step-by-step explanation:
The question relates to a Service Level Agreement (SLA) that defines the timeframe for responding to critical priority cases. A warning is displayed after 15 minutes, and the SLA is considered failed after 30 minutes. If a normal priority case is created at 16:00 and then changed to critical at 16:15, the SLA was already running for 15 minutes before the priority was changed. As per the conditions, the SLA will fail 30 minutes after being set to critical. Therefore, from the time the priority is changed to critical, there are 30 minutes until the SLA fails. Since 15 minutes have already elapsed since the case was created, an additional 15 minutes will be the total time elapse before the SLA fails once the priority is set to critical. Hence, the correct answer is A. 15 minutes.