instruction:
Given an trivia question precisely answer the question with a word/phrase/name. External resources such as Wikipedia could be used to obtain the facts.
question:
Which king experienced regicide at the hands of Shakespeare's Macbeth?
answer:
king duncan


question:
Who hit No.1 with Hollaback Girl in 2005?
answer:
gwen stefani


question:
Which element does 'K' represent in the Periodic Table?
answer:

potassium