There are numerous unsubstantiated reports that natural vitamins are superior to synthetic ones, that fertilized eggs are nutritionally superior to unfertilized eggs, that untreated grains are better than fumigated grains, and the like.

　　The word "unsubstantiated" is closest in meaning to which of following?

　　(A) unbelievable

　　(B) uncontested

　　(C) unpopular

　　(D) unverified