Vаntаge Grid's cоntrоl-rоom softwаre detects that black ice has formed on an exposed outdoor sensor housing and, in response, automatically switches to a backup heating element to keep the sensor's readings accurate, preventing a bad reading from ever reaching the grid-control algorithm. An engineer new to resilience terminology asks whether this is a resilience requirement, a safety requirement, or both. What does the source material's own black-ice example suggest about answering that question?