How many program files does the PLC processor automatically open when a project is first created?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (C)

When a PLC starts up, the runtime brings in several essential blocks that make the system run reliably: a main block that executes in a continuous cycle, a startup or initialization block to set up I/O and internal state at power-on, and a system or diagnostic block that handles background tasks, timing, and fault handling. Because you need initialization to happen before normal operation, ongoing control to continue, and system-level support to keep everything running smoothly, three program files are opened automatically when a new project is created. Other counts would miss one of these critical roles or introduce unnecessary complexity, so three is the standard default.