Answer
D.C. United was the MLS team that signed Freddy Adu to his first professional contract. Adu, a highly touted young player, joined the team in 2004 at the age of 14, becoming the youngest player to ever sign an MLS contract. He made his debut for the team that same year and went on to have a successful career with D.C. United, scoring 11 goals in 81 appearances.