Answer: The Basque language (option A) is NOT part of the Indo-European language family.
Explanation: The Basque language is not part of the Indo-European language family, unlike the other options (Spanish, Welsh, and Icelandic). The Indo-European language family is one of the world's largest language families, encompassing a vast number of languages spoken in Europe, Asia, and other parts of the world. Spanish, Welsh, and Icelandic all belong to the Indo-European language family:
Spanish is a Romance language, which evolved from Latin and is part of the Italic branch of the Indo-European family.
Welsh is a Celtic language, belonging to the Celtic branch of the Indo-European family.
Icelandic is a North Germanic language and is also a member of the Indo-European family.
The Basque language, on the other hand, is an isolated language with no known genetic relationship to any other language family. It is unique to the Basque Country, which straddles the border of Spain and France. Basque is a language isolate, which means it has no known connections to other languages, including Indo-European languages. This makes it distinct from the other languages mentioned and is the reason why Basque is not part of the Indo-European language family.