For this chain-of-thought reasoning and answer, what was the question?
The relevant sentence in the passage is: Overall, thirty-two different drivers have won the Championship, with Richard Petty, Dale Earnhardt, and Jimmie Johnson hold the record for most titles at seven.
 A: Richard Petty
Q: Overall, thirty-two different drivers have won the Championship, with Richard Petty, Dale Earnhardt, and Jimmie Johnson hold the record for most titles at seven. Johnson has the record for most consecutive Drivers' Championships, winning five from 2006 to 2010. Thus far, every champion has originated from the United States.

Based on this passage, who has won the most championships in nascar?