<prompt> A study revealed that in study group, intake of carotene ca colon but it is due to fibre intake, This is due toSampling errorEastogical factorMisclassification biasConfounding factor  <response>: A confounding factor is defined as one which is associated both with exposure and disease, and is distributed unequally in study and control groups. More specifically a confounding factor is one that, although associated with exposure under investigation, is Itself, independently of any such association, a risk factor for the disease. Ref : Park 23rd edition Pgno : 72 