a Demi Lovato

b Katy Perry

c Lady Gaga

d Britney Spears

a Rihanna

b Jennifer Lopez

c Selena Gomez

d Miley Cyrus

a One Direction

b Big Time Rush

c 5 Seconds Of Summer

d The Vamps

a David Guetta

b Mika

c Maitre Gims

d Stromae

a Little Mix

b Ariana Grande

c Jennifer Lopez

d Jessie J