Final answer:
In an exam, use the vertical LRAS curve for long-term economic analysis at full employment, and the upward-sloping SRAS curve for short-term economic changes due to demand shifts.
Step-by-step explanation:
When deciding which LRAS curve should be used in an exam context, it is vital to understand the distinction between short-run aggregate supply (SRAS) and long-run aggregate supply (LRAS). The SRAS curve is typically upward sloping and reflects short-term fluctuations in production where output can exceed or fall short of potential GDP due to variations in demand. Conversely, the LRAS curve is vertical and located at potential GDP, indicating the maximum sustainable output an economy can produce in the long run, at which all resources are fully employed.
In an exam, if the question pertains to the economy's behavior over a longer period or focuses on production at full employment, the vertical LRAS curve is appropriate. For short-term economic analysis, especially if the situation involves short-term demand shifts affecting output levels, the SRAS curve with its upward slope would be the correct choice.