Correct answer: D — Green
Identifying the protective conductor
The supplied paper identifies green as the earthing-wire colour. This follows the traditional colour convention used in many Indian electrical-examination questions. Of the listed choices, green is the intended identification for the protective earthing conductor.
An earthing conductor connects exposed conductive equipment parts to the protective-conductor system. Its role is different from the neutral: the neutral can carry normal load-return or imbalance current, whereas the protective conductor serves the protective bonding and fault-current function.
Colour identification enables installers and maintenance personnel to distinguish these functions. In modern standardized wiring practice, the green-and-yellow combination is widely used to identify protective conductors. Plain green in a historical multiple-choice question should therefore be understood in that examination context, rather than treated as a complete specification for every present-day installation.
For this PYQ, select D — Green, as marked in the source. For actual wiring, conductor identification must follow the applicable installation standard and documentation; colour alone is not proof that a conductor is safely connected or de-energized.
