Which of the following is an example of a source of power requirement for VFR Night?

The correct answer is a battery because it serves as a primary source of electrical power for essential aircraft lighting systems required for VFR Night operations. During night flights under Visual Flight Rules (VFR), aircraft must have operational lights for safety and visibility, ensuring both the pilot can see and be seen. The battery provides immediate, reliable power that is critical, especially during the initial flight phases or if the other power sources falter.

While generators, alternators, and auxiliary power units are important components in an aircraft's electrical system, they primarily serve as secondary or supplementary sources of power. Generators and alternators generate electricity while the engine is running but are not standalone power sources during power failures or specific scenarios when the engine isn’t operating. An auxiliary power unit helps provide electrical power but is generally used for ground operations and may not be a direct requirement for VFR Night flying. Thus, the battery's role as a dependable source of power for critical VFR Night requirements makes it the best answer.