What is one key effect of a swept wing design during high-speed flight?

A swept wing design is primarily beneficial during high-speed flight because it helps delay the onset of the critical Mach number, which is the speed at which airflow over the wing reaches Mach 1. This is achieved by altering the effective angle of attack of the wing and reducing the amount of airflow that exceeds the speed of sound over the wing's surface. As a result, swept wings are particularly useful for high-speed aircraft, allowing them to operate efficiently without encountering significant aerodynamic issues associated with shock waves, such as drag rise and loss of control.

In contrast, the other options do not accurately describe the primary advantages of a swept wing design in the context of high-speed flight. Enhanced lift due to increased surface area is more associated with wing size or shape rather than sweep angle. Increasing control responsiveness at low speeds does not pertain to the high-speed strengths of swept wings, as their design is aimed for efficiency in fast regimes. Additionally, reducing wing loading relates to the distribution of weight across the wing area but isn’t a direct consequence of the wing's sweep angle at high speeds. Thus, the unique characteristic of swept wings in delaying critical Mach makes option B the most relevant choice in this scenario.