Immigration means () A. Studying abroad B. Traveling abroad C. Working in Chinese embassies abroad D. Living abroad and joining the country.

Narrow the meaning of immigration to people who have moved from one country to another, then all countries have their own laws and regulations on foreigners entering their own countries, commonly known as immigration law, and some countries also call it alien residence law. As long as the visa and residence procedures are handled in accordance with the laws of the destination country, they are legal immigrants, otherwise they are illegal immigrants, while modern immigrants refer to people who have settled abroad and joined the nationality of that country.

Therefore, choose: d.