The correct answer is D. no article.
The United States is a proper noun, which means it refers to a specific place. Proper nouns are always capitalized and do not take articles.
Here are some examples of proper nouns:
- The United States
- Canada
- Mexico
- China
- Japan
- Italy
- France
- Germany
- Russia
- India
- Brazil
- Argentina
- Australia
- New Zealand
Here are some examples of common nouns:
- country
- city
- town
- village
- state
- province
- territory
- island
- continent
- ocean
- sea
- river
- lake
- mountain
- hill
- valley
- desert
- forest
- jungle
- grassland
- tundra
- ice sheet
Common nouns are not capitalized and can take articles.
For example, you could say "I went to a country in Europe." or "I went to the United States."
In the sentence "Subhranil went to . . . . . . . . United States to spend the holidays," the word "United States" is a proper noun, so it does not take an article.
