What is checked regarding the battery and electrical system during an inspection?

The correct choice focuses on the importance of ensuring that battery terminals are clean and that connections are secure and free from corrosion. This is vital for the efficient operation of the vehicle's electrical system. Dirty or corroded battery terminals can lead to poor electrical connections, causing issues such as difficulty starting the vehicle, dimming lights, or malfunctioning electrical components.

A clean connection allows for optimal electrical flow, ensuring that various vehicle systems operate correctly and reducing the risk of breakdowns. Regular inspections emphasize the necessity of maintaining these connections to prevent safety hazards and promote vehicle reliability.

The other options do not align with standard inspection practices. For instance, while battery performance is important, replacing the battery every year is not a requirement and can lead to unnecessary costs. The idea that the battery should always be fully charged fails to take into account the natural discharge that occurs; thus, it is more crucial to ensure the electrical system operates efficiently rather than focus solely on the battery's charge state. Lastly, including a backup battery is not a standard requirement for most vehicles during regular inspections, making it less relevant in this context.