Question: "Medusa" is the eighth episode of the second season from The CW television series "Supergirl", which aired on which date, the episode features a minor tie-in with the Arrowverse crossover event "Invasion!"?
{'answer': 'November 21, 2016', 'supporting_facts': [['Medusa (Supergirl)', 0], ['Invasion! (Arrowverse)', 1]]}