 (፩) ብዙ ወካዮች ሁነው ለጋራ ጒዳያቸው የወከሉትን ተወካይ አንዱ ብቻ ሊሽረው አይችልም።
C) there are often a number of factors not under the control of the individual that will hinder the ability of any model to predict behaviour perfectly.