The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

Every culture in the world believes certain superstitions. Even societies that are very rational and scientific are sometimes a little superstitious. For example, Americans consider “13” an unlucky number. Some people in the U.S. also believe that if Friday falls on the thirteenth day of the month, they will have bad luck.
It can be said that superstitions （） in every society.