The telegraph changed society by facilitating communications among Americans. The telegraph gave Americans the chance to send and receive messages at an unprecedented speed and volume. Professor Samuel Morse, an instructor at New York University, created the first version of the telegraph in the 1830s, and, although well-planned, the device required significant revisions before allowing communications between the East and West coasts and eventually overseas
he made them believe it occurs naturally, not magically.
The correct answer here is the public opinion.
All of the methods mentioned here are ways the politicians may test and see the public opinion. Polls are maybe the main indicator of the public opinion next to voting results but at stage it is a bit late for the candidate. Direct contact with the population is also a method by which the politicians can learn what troubles the said population.