Look at the graphic from Citizenship.

Top: Citizenship isn't just about voting once every few years. Democracy works best when citizens get involved in government. There are several ways citizens can participate. They can send letters to their lawmakers or speak out about something important to them. A dump truck dumps a load of letters on two people in suits. One says,

What central idea in Citizenship is emphasized by the image of the letters?

A In a democracy, it is important for people to express their views.
B When people vote, it is like sending a letter to the government.
C Writing is a way that people can share their feelings and ideas.
D Participating in government includes writing letters to politicians.