Correct Answer:
B. Finland
The correct answer is Finland. In 2022, following Russia's full-scale invasion of Ukraine, Finland, a Nordic country, applied for and was invited to join NATO. Finland officially became the 31st member of the alliance in April 2023. Sweden also applied for membership at the same time but faced delays in its accession process. Ireland is not a Nordic country and maintains a policy of military neutrality, thus it was not invited to join NATO.