Question: Columbus Crew SC is head coached by which retired soccer player?

Context paragraphs:
Columbus Crew SC: Columbus Crew Soccer Club is an American professional soccer club based in Columbus, Ohio.  The Crew competes in Major League Soccer (MLS) as a member club of the league's Eastern Conference.  The Crew began play in 1996 as one of the ten charter clubs of the league.  The team is owned by Anthony Precourt and Precourt Sports Ventures LLC.  Precourt became the second owner in the history of the club on July 30, 2013.  The club's head coach is Gregg Berhalter, a former player of the United States men's national soccer team.

Mapfre Stadium: Mapfre Stadium ( ; styled as "MAPFRE Stadium"), previously known as Columbus Crew Stadium, is a soccer-specific stadium in Columbus, Ohio, United States.  It primarily serves as the home stadium of the Columbus Crew SC of Major League Soccer.  Mapfre Stadium is also the site of a variety of additional events in amateur and professional soccer, American football, lacrosse, and rugby, and is a regular site for outdoor concerts due to the permanent stage in the north end zone.

Alex Crognale: Alex Crognale (born August 27, 1994) is an American professional soccer player who plays as a defender for Columbus Crew SC in Major League Soccer.

Niko Hansen: Nikolaj "Niko" Hansen (born September 14, 1994) is a Danish-American professional soccer player who plays as a winger for Columbus Crew SC in Major League Soccer.

Adam Jahn: Adam Jahn (born January 5, 1991) is an American soccer player who plays as a forward for Columbus Crew SC in Major League Soccer.

Zack Steffen: Zackary Thomas Steffen (born April 2, 1995) is an American soccer player who currently plays as a goalkeeper for Columbus Crew SC in Major League Soccer.

Josh Wolff: Joshua David "Josh" Wolff (born February 25, 1977) is a retired American soccer player who now works as an assistant coach for Columbus Crew SC of Major League Soccer.

Gregg Berhalter: Gregg Berhalter ( ; born August 1, 1973) is a retired American soccer player and current head coach of Columbus Crew SC in Major League Soccer.

List of Columbus Crew head coaches: Columbus Crew SC is a professional soccer team in the United States.  The team is a member of the Eastern Conference of Major League Soccer, the top professional soccer league of the United States and Canada.  Crew SC has had five different head coaches since joining the league in 1996.  Timo Liekoski, the only Finnish head coach in MLS history, was the first head coach in 1996, but started 6-16 and was fired midseason to be replaced by Tom Fitzgerald.  Fitzgerald is currently the all-time leader in regular season wins (70), playoff appearances (four) and playoff wins (nine).

Conor Casey: Conor Patrick Casey (born July 25, 1981) is an American retired soccer player who last played as a forward for Columbus Crew SC in Major League Soccer.  He is known as a strong, physical striker with a deceptively deft touch.

Supporting paragraphs: Columbus Crew SC Gregg Berhalter
Answer: Gregg Berhalter