Which one of the following countries is a kingdom ?

Thailand is a kingdom, specifically a constitutional monarchy, where the King serves as the head of state [t1][t3]. A unified Thai kingdom was established in the mid-14th century, and while it transitioned from an absolute monarchy to a constitutional one in 1932, it remains a monarchy today [t1][t5]. In contrast, Egypt is a republic (Arab Republic of Egypt), Lebanon is a parliamentary republic, and Vietnam is a socialist republic [t1][t7]. According to political classification, a monarchy is defined by a head of state who holds a hereditary position, whereas a republic features an elected head of state [c2]. While countries like Nepal and the Maldives were once monarchies or sultanates, they have since transitioned into republics [c1][c5]. Thailand, however, maintains its status as a kingdom with the King exercising constitutional powers [t3][t4].

Sources

1. [1] https://user.iiasa.ac.at/~marek/fbook/05/geos/th.html
2. [2] https://www.bbc.com/news/world-asia-15581957
3. [3] https://www.cia.gov/the-world-factbook/about/archives/2021/field/government-type
4. [4] Indian Polity, M. Laxmikanth(7th ed.) > Chapter 5: Preamble of the Constitution > 1:1 1 Republic > p. 45
5. [5] Indian Constitution at Work, Political Science Class XI (NCERT 2025 ed.) > Chapter 1: CONSTITUTION: WHY AND HOW? > Debate over Constitution making in Nepal: > p. 12
6. [6] Contemporary World Politics, Textbook in political science for Class XII (NCERT 2025 ed.) > Chapter 3: Contemporary South Asia > Contemporary South Asia 31 > p. 31
7. [7] https://en.wikipedia.org/wiki/Monarchy_of_Thailand