What must be true for a malfunction to occur?

For a malfunction to occur, it is essential that the failure is sudden and unavoidable. This concept emphasizes that a malfunction typically manifests itself without prior indication or warning, making it unexpected for those operating or managing the system. Sudden failures could be due to unforeseen circumstances or unexpected wear and tear that surpasses anticipated tolerances. This highlights the unpredictable nature of malfunctions, which can lead to operational challenges, safety concerns, or the need for immediate intervention.

The other options focus on different aspects that may not necessarily lead to a malfunction. For instance, maintenance issues can certainly contribute to failures but do not define the occurrence of a malfunction by themselves. Similarly, the age of a facility or the severity of the failure being minor does not inherently lead to a malfunction either. Therefore, the critical component for understanding a malfunction lies in its sudden and unavoidable nature, as represented by the correct choice.