OKLAHOMA CITY, 2017-Feb-09 — /EPR Retail News/ — Sonic Corp. (NASDAQ:SONC), the nation's largest chain of drive-in restaurants, today (Feb 8, 2017) announced that Todd Smith, president and chief marketing officer, will resign from the position effective March 9, 2017. Smith will serve in a transition role through that date and then will pursue an entrepreneurial…