Topic: Synonyms, Subject: English Grammar (ইংরেজি গ্রামার)

Best Answer Explained in Below-:

The word ‘alliance’ refers to a formal agreement or association between two or more parties, often for mutual benefit or cooperation in a specific area, such as politics, military, or business. This concept of coming together to achieve common goals is inherently captured in the synonym 'association.'

Choosing 'association' (option C) effectively conveys the essence of ‘alliance’ as it emphasizes collaboration and the establishment of a relationship based on shared interests. In contrast, the other options fail to reflect this concept. 'Enmity' (option A) signifies hostility or opposition, which is contrary to the cooperative nature of an alliance. 'Alien' (option B) denotes a sense of foreignness or disconnection, while 'separation' (option D) indicates a division or distancing between entities, again contrary to the idea of unity in an alliance.

Therefore, 'association' encompasses the fundamental idea of partnership and alignment that an 'alliance' represents, making it the correct synonym in this context.