Which of the following was introduced by the Britishers primarily for maintaining law and order in India during the colonial era?

Electric Telegraph System

The correct answer is Option 3: Electric Telegraph System

The Electric Telegraph System was introduced by the British primarily for maintaining law and order in India during the colonial era. It was used for rapid communication, which was crucial for managing administrative and security concerns across the vast and diverse territories of British India. Railways, postal services, and other infrastructure developments, while important, were not specifically introduced for law and order purposes.