"Crazy in Love" was re-recorded by Beyoncé for the film Fifty Shades of Grey (2015) and used for its trailer which was released on July 24, 2014. This slowed-down version was produced by Boots with violin arrangements by Margot, both of whom worked on Beyoncé's self-titled fifth studio album (2013), and unlike the original, does n't feature Jay-Z. Margot said: "It inspires me to work on other artists' songs (because) it pushes my boundaries in a direction that I would n't necessarily come up with. Obviously I know how' Crazy in Love' goes, but I knew there was the possibility her vocals would be different. It's almost more vulnerable and beautiful this way, because you do do crazy things when you fall in love. To hear the mood reversed and flipped makes it even more powerful."

Answer this question based on the passage: who sang crazy in love for fifty shades of grey? Okie... think carefully first, then make a decision:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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To answer the above question, the relevant sentence is: "Crazy in Love" was re-recorded by Beyoncé for the film Fifty Shades of Grey (2015) and used for its trailer which was released on July 24, 2014. So, the answer is Beyoncé.