Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
--------
Question: The Church of the Savior on Spilled Blood, built on the site of the assassination of Tsar Alexander II, is in which Russian city?

Answer: church of the savior on blood


Question: Which river begins in the Rocky Mountains in south-west Colorado, crosses New Mexico and forms the border between Mexico and the USA before reaching the Gulf of Mexico?

Answer: new mexico


Question: What proper noun links titles by Bjork, Bananarama, Shocking Blue and Mark Wynter?

Answer:
shocking blue