What is the primary goal of an examination in the context of immigration checks?

In the context of immigration checks, the primary goal of an examination is to determine if a person is a US citizen or alien. This process is crucial because it establishes the individual's legal status upon entering or residing in the country. Understanding whether someone is a citizen helps in applying the correct legal standards and protections that apply to them and ensures that immigration laws are upheld. Identifying citizenship status is foundational to various subsequent actions taken by immigration officials, including the issuance of visas, residency permits, or further legal processes for non-citizens.

While the other options address important aspects of border control and safety—such as checking for illegal substances, verifying travel documentation, and enforcing customs regulations—they do not directly relate to the central concern of establishing an individual's legal status in the context of immigration checks. Travel documentation checks, for example, help ensure that an individual has the appropriate papers to enter the country but do not specifically assess their citizenship. Thus, the focus on citizenship status through examination underlines the overarching intent of immigration enforcement and regulation.