Final answer:
A visa is the document needed to show permission to study, travel, or work in the US.
Step-by-step explanation:
The document that people need to show they have permission to study, travel, or work in the US is called a visa. A visa is a government-issued document that allows individuals to enter, stay, or work in a particular country for a specific period of time. In the case of the United States, there are different types of visas depending on the purpose of the visit, such as student visas, tourist visas, or work visas.
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