The core concept here is 'assimilation', which specifically refers to the process where individuals or groups adopt the cultural traits of another group, often leading to a loss of their original cultural identity. Option A is correct because it directly defines assimilation. Option B is misleading as it suggests a complete rejection of one's culture, which is not the essence of assimilation. Option C describes cultural blending, which is more akin to multiculturalism than assimilation. Option D contradicts the concept of assimilation, which involves adopting traits rather than preserving distinct identities.