What criteria must the electric plug meet?

Answer: C — Must be locked and in good condition

The electric plug must be locked and in good condition to ensure a secure and reliable connection. A secure plug is essential for the safe operation of any electrical system, especially in commercial vehicles. When the plug is locked, it helps prevent accidental disconnection, which could lead to power loss or malfunction of critical systems during vehicle operation. Additionally, a plug in good condition means there are no signs of wear, damage, or corrosion that could hinder electrical conductivity. It's important for the plug connections to be clean and intact, as any deficiencies can compromise the functioning of electric systems in the vehicle. Proper maintenance of the plug assures that the vehicle operates efficiently and safely.