Detailed Instructions: In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it. Your job is to determine which sentence(s) from the passage can be used to search for further information needed to answer the question.
Problem:Question: What year did Pasha found the revolutionary movement that Ertegun later joined? Passage:Born in Constantinople to a civil servant father, Mehmet Cemil Bey, and a mother Ayşe Hamide Hanım, who was a daughter of Sufi shaykh İbrahim Edhem Efendi, he studied law at Darülfünûn-u Şahâne (دار الفنون شهانه), now Istanbul University, and graduated in 1908. He was a legal counsel for the Ottoman Ministry of Foreign Affairs, when he saw the birth of his first son, Nesuhi, on 26 November 1917, in Constantinople (now Istanbul), during the First World War. Taking part in an Ottoman delegation with a mission to search reconciliation with the Nationalists in Ankara, by the end of 1920, changed his destiny. While the two Ottoman Ministers heading the delegation returned to Istanbul after not achieving an understanding with the revolutionaries led by Mustafa Kemal Pasha he chose to join the National Struggle and remained in Ankara, leaving behind his young wife and three-year-old son, Nesuhi. He became an aide to Mustafa Kemal during the Turkish War of Independence and the chief legal counsel of the Turkish delegation to the resulting Treaty of Lausanne in 1923.

Solution:
While the two Ottoman Ministers heading the delegation returned to Istanbul after not achieving an understanding with the revolutionaries led by Mustafa Kemal Pasha he chose to join the National Struggle and remained in Ankara, leaving behind his young wife and three-year-old son, Nesuhi