Patricia ``Tricia'' Nixon Cox (born February 21, 1946) is the elder daughter of the 37th U.S. President Richard M. Nixon and First Lady Pat Nixon, and sister to Julie Nixon Eisenhower. In _her_ father's public career, Cox performed a ceremonial role, in contrast to her younger sister Julie Nixon Eisenhower's more political involvement. <sep>, Pronoun: her <sep>, A: Julie Nixon Eisenhower <sep>, B: Cox