PROVIDENCE — Don Carlson dropped out of Rhode Island’s First Congressional District race on Sunday, just nine days before the Democratic primary and two days after defending his conduct with a student at Williams College while he was a professor there in 2019. Carlson responded in a video statement Friday to the allegation in an investigative report by WPRI 12, which said Carlson was asked not to return to teach at the college after he allegedly sent a text message to a graduating senior in which “he suggested a relationship modeled on a website where people can pay to...