Read the following passage carefully and choose the most appropriate answer to the question out of the four alternatives. <br />To avoid the various foolish opinions to which mankind are prone, no superhuman brain is required. A few simple rules will keep you free, not fromall errors, but from silly errors. If the matter is one that can be settled by observation, make the observation yourself. Aristotle could haveavoided the mistake of thinking that women have fewer teeth than men, by the simple device of asking Mrs. Aristotle to keep her mouth openwhile he counted. Thinking that you know when in fact you do not is a bad mistake, to which we are all prone. I believe myself that hedgehogs eatblack beetles, because I have been told that they do; but if I were writing a book on the habits of hedgehogs, I should not commit myself until Ihad seen one enjoying this diet. Aristotle, however, was less cautious. Ancient and medieval writers knew all about unicorns and salamanders;not one of them thought it necessary to avoid dogmatic statements about them because he had never seen one of them. The attitude of the author is