You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

what is the first event mentioned?, Context: The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. Following the abdication of Nicholas II of Russia, the Russian Provisional Government was established. In October 1917, a red faction revolution occurred in which the Red Guard, armed groups of workers and deserting soldiers directed by the Bolshevik Party, seized control of Saint Petersburg (then known as Petrograd) and began an immediate armed takeover of cities and villages throughout the former Russian Empire.
Solution: Russian Revolution
Why? This is a good example, and the Russian Revolution is the first event mentioned.

New input: How would one determine what their rights were in this land?, Context: Until the death of Sigismund II Augustus, the last king of the Jagiellonian dynasty, monarchs could be elected from within only the royal family. However, starting from 1573, practically any Polish noble or foreigner of royal blood could become a PolishLithuanian monarch. Every newly elected king was supposed to sign two documentsthe Pacta conventa ("agreed pacts")a confirmation of the king's pre-election promises, and Henrican articles (artykuy henrykowskie, named after the first freely elected king, Henry of Valois). The latter document served as a virtual Polish constitution and contained the basic laws of the Commonwealth:
Solution:
Polish constitution