The correct answer is option 1, 1851. This means that the first telegraph line in India was started in the year 1851. A telegraph line is a system that allows messages to be transmitted long distances using electrical signals. Option 2, 1875, is incorrect as it is not the earliest date mentioned. Option 3, 1884, and option 4, 1900, are also incorrect as they are later dates than the correct answer. It is important to pay attention to the accuracy of dates when answering historical questions.