Answer:
1st Amendment; Freedom of Speech.
Step-by-step explanation:
The First Amendment found in the American Constitution is the most important and most essential to the survivability of a democracy. A democracy is "made by the people, made up of people, for the people, and under while ruling the people". Without the Freedom of Speech, there would not be any of the other Amendments.
Take for example:
2nd Amendment: The Second Amendment is based off of the 1st Amendment in that the people have the right to have a voice, and that voice back then said that the ordinary citizen needs the right to arms to protect themselves from outside forces that try to invade the US.
3rd Amendment: The Third Amendment is based off the 1st Amendment, in that the people have the "right", and that, in this case, it lays out the foundation that the citizen has the right of ownership of their houses, and that soldiers cannot be housed in citizen's houses unless in wartime.
etc. etc.
While all of these are important, you can see that each of these are based off the 1st Amendment, or the person's right to what they think, believe, etc. in which it cannot be suppressed.
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