Given the task definition, example input & output, solve the new input case.
In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Example: 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.
Output: Russian Revolution
This is a good example, and the Russian Revolution is the first event mentioned.

New input case for you: What rock group was mentioned before Abba?, Context: Towards the center, at the end of the groove, there is another wide-pitched section known as the lead-out. At the very end of this section the groove joins itself to form a complete circle, called the lock groove; when the stylus reaches this point, it circles repeatedly until lifted from the record. On some recordings (for example Sgt. Pepper's Lonely Hearts Club Band by The Beatles, Super Trouper by Abba and Atom Heart Mother by Pink Floyd), the sound continues on the lock groove, which gives a strange repeating effect. Automatic turntables rely on the position or angular velocity of the arm, as it reaches the wider spacing in the groove, to trigger a mechanism that lifts the arm off the record. Precisely because of this mechanism, most automatic turntables are incapable of playing any audio in the lock groove, since they will lift the arm before it reaches that groove.
Output:
The Beatles