Distinguish between a primary battery and a backup battery in aircraft power architecture and their typical use scenarios.

• A. Primary battery used for engine start or initial power; backup battery supplies essential loads during extended power loss or during start sequences for critical times.
• B. Primary battery used for emergencies only; backup battery for engine start.
• C. They are the same; no distinction.
• D. Primary battery used to supply avionics while backup powers the hydraulics.

Answer: (A)