Article: In an interview published by Vogue in April 2013, Beyoncé was asked if she considers herself a feminist, to which she said, "that word can be very extreme... But I guess I am a modern-day feminist. I do believe in equality". She would later align herself more publicly with the movement, sampling "We should all be feminists", a speech delivered by Nigerian author Chimamanda Ngozi Adichie at a TEDxEuston conference in April 2013, in her song "Flawless", released later that year. She has also contributed to the Ban Bossy campaign, which uses television and social media to encourage leadership in girls.

Now answer this question: What campaign did she contribute to?
Ban Bossy