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).
Refer to the input text as context and select the correct relationship between 'Marathon Oil' and 'Petroleum' from the available options.
Options: founded by, stock exchange, operator, product/material produced