Given the task definition and input, reply with output. In this task, you are given a context, a subject, a relation, and many options. Based on the context, from the options select the object entity that has the given relation with the subject. Answer with text (not indexes).

Context: Field Marshal Prince Bhanurangsi Savangwongse , The Prince Banubandhu Vongsevoradej ( 11 January 1859 -- 13 June 1928 ) ( Thai : ) was a son of HM King Mongkut of Siam and HM Queen Debsirindra . Although the Prince held a number of posts in the government of his elder brother , King Chulalongkorn , including the post of Commander - in - Chief of the Royal Siamese Army , he is best remembered as the founder of the Thai postal service . His most famous son is the Formula One racer , Prince Birabongse Bhanutej Bhanubandh , better known as Prince Bira ., Phra Bat Somdet Phra Poraminthra Maha Chulalongkorn Phra Chunla Chom Klao Chao Yu Hua, or Rama V (20 September 1853 23 October 1910), was the fifth monarch of Siam under the House of Chakri. He was known to the Siamese of his time as "Phra Phuttha Chao Luang" (, the Royal Buddha). His reign was characterized by the modernization of Siam, governmental and social reforms, and territorial concessions to the British and French. As Siam was threatened by Western expansionism, Chulalongkorn, through his policies and acts, managed to save Siam from colonisation. All his reforms were dedicated to ensuring Siam's survival in the face of Western colonialism, so that Chulalongkorn earned the epithet "Phra Piya Maharat" (, the Great Beloved King)., Queen Debsirindra of Siam, formerly Queen Ramphoei Phamaraphirom, born Princess Ramphoei Siriwong (17 July 1834 9 September 1861) was the second consort of King Mongkut, and mother of King Chulalongkorn., Phra Bat Somdet Phra Poramenthra Maha Mongkut Phra Chom Klao Chao Yu Hua, or Rama IV, known in English-speaking countries as King Mongkut (18 October 18041 October 1868), was the fourth monarch of Siam (Thailand) under the House of Chakri, ruling from 1851 to 1868. , Subject: bhanurangsi savangwongse, Relation: country_of_citizenship, Options: (A) british (B) siam (C) thailand
thailand