Which of the following should be classified according to sources that are no longer relevant?

The classification of information typically relies on its relevance and the sources from which it originates. When considering this, the appropriate choice would be "None of the above" because all provided options (current affairs, historical data, and released materials) pertain to sources that still hold importance based on their context and use.

Current affairs are ongoing events that can influence recent intelligence assessments - thus, they are relevant for classification purposes. Historical data may still provide significant insights into current contexts and decision-making based on past lessons learned, which makes it relevant. Released materials often contain information that is no longer classified but retains some sensitivity or significance even after release, depending on context.

Therefore, the answer "None of the above" aligns with the concept that these categories of information can still be classified or assessed based on their context and relevance, rather than being deemed obsolete purely based on their source timeframe. This understanding reinforces the importance of assessing information holistically, rather than dismissing it solely based on when the source originated.