Both Marathon Petroleum and Phillips 66 were the downstream arms spun off from their parents in 2011 — Houston-based Marathon Oil Corp. (NYSE: MRO) and Houston-based ConocoPhillips (NYSE: COP).
Take context from the input text and decide on the accurate relationship between 'Marathon Oil' and 'Petroleum' from the options provided.
Options: operator, stock exchange, product/material produced, founded by