Which condition would cause the engine to stop during flight?

Fuel starvation is a condition where the engine is no longer receiving the necessary fuel to continue its operation, leading to engine failure during flight. This can occur due to various reasons, such as an empty fuel tank, fuel line blockage, or issues with the fuel pump. When the engine does not receive an adequate fuel supply, the combustion process is interrupted, causing the engine to stop running completely.

Understanding the risk factors for fuel starvation is crucial for any pilot, as it highlights the importance of pre-flight planning, fuel management, and constant monitoring of fuel levels during flight. Being aware of the fuel system's condition and how to troubleshoot such issues can help prevent a potentially dangerous situation in flight.

In contrast, other conditions such as gear retraction or vacuum loss can impact flight safety, but they do not directly lead to engine failure. Excessive altitude could also lead to performance issues, but it doesn’t inherently cause the engine to stop running like fuel starvation does. Thus, fuel starvation stands out as the most direct cause of engine stoppage in this context.