Former “Fox & Friends” co-host Gretchen Carlson alleged in an explosive lawsuit filed Wednesday that Fox News Chairman and CEO Roger Ailes fired her for rebuffing his sexual advances and challenging a sexist newsroom culture. Carlson, who spent 11 years at the network, described being ostracized and marginalized by Fox News for pushing back against condescending treatment. After seven and a half years as a co-host on “Fox & Friends,” the top-rated cable morning news show, Carlson was reassigned in 2013 to an early afternoon time slot. Fox News terminated her employment on June 23.