In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Let me give you an 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.
The answer to this example can be: Russian Revolution
Here is why: This is a good example, and the Russian Revolution is the first event mentioned.

OK. solve this:
What groups can be found in the concert hall west of Back Bay?, Context: Music is cherished in Boston. The Boston Symphony Orchestra is one of the "Big Five," a group of the greatest American orchestras, and the classical music magazine Gramophone called it one of the "world's best" orchestras. Symphony Hall (located west of Back Bay) is home to the Boston Symphony Orchestra, (and the related Boston Youth Symphony Orchestra, which is the largest youth orchestra in the nation) and the Boston Pops Orchestra. The British newspaper The Guardian called Boston Symphony Hall "one of the top venues for classical music in the world," adding that "Symphony Hall in Boston was where science became an essential part of concert hall design." Other concerts are held at the New England Conservatory's Jordan Hall. The Boston Ballet performs at the Boston Opera House. Other performing-arts organizations located in the city include the Boston Lyric Opera Company, Opera Boston, Boston Baroque (the first permanent Baroque orchestra in the US), and the Handel and Haydn Society (one of the oldest choral companies in the United States). The city is a center for contemporary classical music with a number of performing groups, several of which are associated with the city's conservatories and universities. These include the Boston Modern Orchestra Project and Boston Musica Viva. Several theaters are located in or near the Theater District south of Boston Common, including the Cutler Majestic Theatre, Citi Performing Arts Center, the Colonial Theater, and the Orpheum Theatre.
Answer:
Boston Symphony Orchestra, (and the related Boston Youth Symphony Orchestra, which is the largest youth orchestra in the nation) and the Boston Pops Orchestra