Premise: Gwen Stefani . She is the co-founder and lead vocalist of the band No Doubt that experienced major success after their breakthrough studio album Tragic Kingdom ( 1995 ) along with various successful singles , including `` Just a Girl '' , `` Do n't Speak '' , `` Hey Baby '' , and `` It 's My Life '' .
Hypothesis: Gwen Stefani is the co-leader of No Doubt.
Label: ENTAILMENT