Article: Beyoncé and husband Jay Z are friends with President Barack Obama and First Lady Michelle Obama. She performed "America the Beautiful" at the 2009 presidential inauguration, as well as "At Last" during the first inaugural dance at the Neighborhood Ball two days later. Beyoncé and Jay Z held a fundraiser at the latter's 40/40 Club in Manhattan for Obama's 2012 presidential campaign which raised $4 million. Beyoncé uploaded pictures of her paper ballot on Tumblr, confirming she had voted in support for the Democratic Party and to encourage others to do so. She also performed the American national anthem at his second inauguration, singing along with a pre-recorded track. She publicly endorsed same sex marriage on March 26, 2013, after the Supreme Court debate on California's Proposition 8. In July 2013, Beyoncé and Jay-Z attended a rally in response to the acquittal of George Zimmerman for the shooting of Trayvon Martin.

Now answer this question: Beyonce and Jay-Z went to a rally for the acquittal of whom?
George Zimmerman