Fill in the blank with the correct option.
The United States of America ________ of people of all nationalities.

The correct answer is Option D (consists).

Key Points:
• Concept: Subject-Verb Agreement with Proper Nouns. Names of countries, even when ending in '-s' or sounding plural (e.g., The United States of America, The West Indies), are singular proper nouns and require a singular verb.
• Explanation: 'The United States of America' is a single sovereign nation (singular subject). Therefore, it takes the third-person singular present verb 'consists'.
• Other Options: 'consist' and 'have consisted' are plural verb forms; 'consisting' is a participle that cannot function as the main verb alone.
• Official Key: Option 4 ('consists') is the correct option according to the official answer key.
• Key Takeaway: Remember: Names of countries (e.g., The United States) take a singular verb.