Option C is the correct answer because an “immigrant “ is a person who comes to live permanently in a foreign country, hence it is correct to say that a person who chooses to live in a foreign country is an immigrant.
Option A is incorrect because a “traveller” is one who visits various places for exploring and travelling to places, hence it is not the same as living permanently in a country.
Option B is incorrect because an “explorer” is someone who goes to new places to explore, which is not the same as permanently living in a country, hence it is incorrect.
Option D is incorrect because a “refugee” is a person who has been forced to leave their country in order to escape war, persecution, or natural disaster, which is not the same as willingly moving to another country permanently, hence it is incorrect.