With the power lever opened for take off power at sea level, the throttle butterfly of an engine fitted with an internal supercharger would be:

When considering the operational characteristics of an engine equipped with an internal supercharger, it is essential to understand how the power lever and throttle butterfly interact during takeoff at sea level.

When the power lever is opened for takeoff power, the throttle butterfly tends to be in a choked position rather than fully open. This situation occurs because the internal supercharger increases the pressure and density of the intake air, allowing the engine to achieve greater power output without requiring maximum throttle opening.

Operating the throttle in a choked position during takeoff ensures that the engine can achieve optimal performance as the supercharger compensates for the lower atmospheric pressure at sea level, allowing for efficient fuel-air mixture and maximizing engine power. A fully open throttle would be unnecessary and could lead to a risk of over-boosting, depending on the engine design and operational context.

In summary, the choked position of the throttle butterfly allows the engine to balance the intake air provided by the supercharger with the required power output for takeoff, making it the correct choice in this scenario.