question: A randomized, double-blinded trial finds that oral corticosteroids are superior to placebo in hastening the resolution of
  otitis media with effusion. Possible reasons why this study might have given a falsely positive result include
opa: The sample size may have been too small
opb: The apparent effect might be a result of chance
opc: Lax inclusion criteria may have led to inclusion of some subjects in the study who did not really have otitis media with effusion
opd: None of the above