Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Kronos (or Cronus) was the Greek equivalent of which Roman god?
cronus

The bells were ringing for Chuck Berry when this song made it to No1. His first and only British No. 1. What song?
chuck berry

Deoxyribonucleic acid is commonly known as what?
deoxyribonucleic acid