Task: Pos Tagging
Input (English): Sentence: The senior policy officer may be moved to think hard about a problem by any of an infinite variety of stimuli : an idea in his own head , the suggestions of a colleague , a question from the Secretary or the President , a proposal by another department , a communication from a foreign government or an American ambassador abroad , the filing of an item for the agenda of the United Nations or of any other of dozens of international bodies , a news item read at the breakfast table , a question to the President or the Secretary at a news conference , a speech by a Senator or Congressman , an article in a periodical , a resolution from a national organization , a request for assistance from some private American interests abroad , et cetera , {{ ad }} infinitum . 
Word: ad
Output (English): X