The correct option is C The Sepoys needed someone to legitimise the revolt and the person in question resided in Delhi.
The Sepoys needed someone to legitimise the revolt and they knew they could find the person in Delhi. This person whom the Sepoys sought was Bahadur Shah Zafar, the Mughal Emperor. With him on their side, the Sepoys knew that the mutiny would become a political struggle which is exactly what the Sepoys wanted.