A "Gallup poll" is a national public opinion poll run by Gallup, Inc. According to
the company's website, a typical sample size for a phone-based Gallup poll is
1000 randomly-selected adults, and poll results are said to be representative of
the opinions of all Americans within a margin of error of +4 percentage points.
What methods do you think Gallup, Inc. must use to ensure true random
selection of all 1000 phone participants? Give at least 3 methods.

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