The passage given below has numbered blanks.Select the most appropriate option to fill in blank number 5. To avoid the various foolish opinions which mankind holds, no superhuman genius is required. A few simple rules will keep you, not from all error, but from silly error. If the matter is one that can be (1)______ by observation, make the observation yourself. Aristotle could have avoided the mistake of (2) ______ that women have fewer teeth than men, by the simple device of asking Mrs Aristotle to keep her mouth open while he (3)______. He did not do so because he thought he knew. Thinking that you know when in fact you don't is a fatal mistake, to which we are all (4)______. I believe myself that hedgehogs eat black beetles, because I have been told that they do; but if I were writing a book on the habits of hedgehogs, I should not (5)______ myself until I had seen one enjoying this unappetizing diet. Aristotle, however, was less cautious. Ancient and medieval authors 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.