have they been involved in any activism?
Yes, Band Aid to raise money for the 1983–85 famine in Ethiopia.
U2
In 1984, Bono and Clayton participated in Band Aid to raise money for the 1983–85 famine in Ethiopia. 
how many members of u2 were born in ireland UNANSWERABLE where was the band formed? Dublin who are its members? Bono, Adam Clayton, the Edge and Larry Mullen Jr. did the band collaborated with anyone? With the band Clannad and for the film "Captive". what kind of style do they adopt in their music? Initially rooted in post-punk, it's musical style has evolved throughout their career. what music form is it? A broad genre of rock music. mention some of its characteristics? The use of bass is prominent on many post-punk records either as a lead instrument by artists like Gang of Four or PiL . was it a well received genre? Yes, the post-punk period produced significant innovations and music on its own. did it achieve fame in the united states? UNANSWERABLE what themes do the band deal with? Social and political themes.
wiki:5364964
U2 [SEP] Activism and philanthropy
Since the early 1980s, the members of U2—as a band and individually—have collaborated with other musicians, artists, celebrities, and politicians to address issues concerning poverty, disease, and social injustice. In 1984, Bono and Clayton participated in Band Aid to raise money for the 1983–85 famine in Ethiopia. This initiative produced the hit charity single "Do They Know It's Christmas?", which would be the first of several collaborations between U2 and Bob Geldof. In July 1985, U2 performed at Live Aid, a follow-up to Band Aid's efforts. Bono and his wife Ali, invited by World Vision, visited Ethiopia that year where they witnessed the famine first-hand.