What does IEC 61131-3 specify for PLC programming?

What does IEC 61131-3 specify for PLC programming?

• A. Guidelines for electrical grounding
• B. Software version control for SCADA
• C. International standard for PLC programming languages, including Ladder Diagram, Function Block Diagram, Structured Text, Instruction List, and Sequential Function Chart.
• D. Procedure for calibration of instruments

Answer: (D)