challenge: What is notable about the album 'Azul' by Los Piojos in terms of its availability?
  
  A. It was released exclusively in the US
  B. It is the only album by Los Piojos that is not available in the US
  C. It is the only one of Los Piojos' four albums available in the US
  D. It is the band's best-selling album in the US
  Answer: 