The correct answer is: A. no article, a
The United States of America is a country. It is in North America.
The article “the” is used before a noun to indicate that the noun is specific or unique. In this case, the United States of America is not a specific or unique country, so the article “the” is not used.
The article “a” is used before a noun to indicate that the noun is general or non-specific. In this case, the United States of America is a general or non-specific country, so the article “a” is used.
The article “no article” is used before a noun to indicate that the noun is not specific or unique. In this case, the United States of America is not a specific or unique country, so the article “no article” is used.