The correct answer is D.
Immigrants affect urban environments in:
- cultural behavior. The immigrants come from a different culture and so they bring with them different set of values and beliefs, a different music, style, literature, theater etc.
- city language. Many immigrants never learn their new country's language and continue to communicate in their own native languages,
- architecture. Many cities change their landscape with the arrival of immigrants as they introduce their own style of living, including their own style of accommodation.
The formation of exclaves has nothing to do with immigrants as an exclave is a part of a country which had separated from the main part, like the Vatican City or San Marino.