(A) This choice does not have to follow from the argument, as a correct inference must. The winner did not have to know how to spell most of the anglicized words in the dictionary, only the ones that she was given.
(B) This choice does not have to follow from the argument, as a correct inference must. All contestants don’t have to find foreign words more difficult. For instance, the child of German parents might find it easy to spell Ursprache.
(C) This choice does not have to follow from the argument, as a correct inference must. In fact, it must follow from the argument that contestants should be judged only by their spelling ability, not by their facility with "all aspects of language."
(D) CORRECT. The author wants to exclude foreign words because spelling bees should be based only on spelling ability, not on "knowledge of linguistics and international phonetics." Thus, the author must believe that spelling foreign words correctly when they are spoken requires knowledge of the phonetics of the foreign language in question.
(E) This choice does not have to follow from the argument, as a correct inference must. While this might be factually true, nowhere in the argument is there any comparison between the number of words in English and that of any other language.