A Roxbury teenager was arrested Wednesday and charged with fatally shooting another teenager in Roxbury in October, Boston police said. Rashawn Clark, 17, was arraigned in Roxbury District Court in connection with the slaying of Andre Matthew, 17, of Roxbury. Prosecutors believe Clark sought out Matthew with the intent of shooting him. Clark also faces several gun charges. He was held without bail, prosecutors said. Matthew was shot Oct.1 near 48 Bower St. Officers arriving at the scene found him suffering from a gunshot wound. He was taken to Boston Medical Center, where he was pronounced dead, police said.