Question: The wife of Mitt Romney co-owns a horse that was ridden by which rider in the 2012 summer Olympics ?

Context paragraphs:
Sam Griffiths: Sam Griffiths is an Australian Eventing rider from Pearcedale in Victoria.  He won the 2014 Mitsubishi Motors Badminton Horse Trials riding Paulank Brockagh who he later went on to ride in the FEI World Equestrian Games.  At the 2012 Summer Olympics he competed in the Individual and Team eventing, but fell during the cross-country event and did not finish.  He was originally selected as the second reserve rider, but entered the team when two other Australian horses were unable to compete.

Ingrid Klimke: Ingrid Klimke (born April 1, 1968 in Münster, Germany) is a German eventing rider.  She appeared at five Olympics from 2000 to 2016.  With her horse Abraxxas, she won two gold medals in team eventing at the 2008 Summer Olympics and the 2012 Summer Olympics.  At the 2016 Summer Olympics, she won a team silver with Hale-Bob.

Snowbound (horse): Snowbound was the first horse to be ridden to an Olympic individual gold medal by an American rider, doing so with rider Bill Steinkraus in the 1968 Summer Olympics in Mexico City.

Peter Thomsen: Peter Thomsen (Born 4 April 1961 in Flensburg, Germany) is a German eventing rider.  He won the gold medal in team eventing at the 2008 Summer Olympics with his horse The Ghost of Hamish, and again at the 2012 Summer Olympics with his horse Barny.

Patrik Kittel: Patrik Kittel (born 10 June 1976 in Österåker, Sweden) is a Swedish horse rider.  He was born in Stockholm.  He competed at the 2008 Summer Olympics in Beijing, where he placed fourth in team dressage.  At the 2012 Summer Olympics he competed in the team dressage events and qualified for the Grand Prix Special and Grand Prix Freestyle, finishing 14th.

Ludvig Svennerstål: Sven Ludwig Svennerstål (born 24 August 1990) is a Swedish equestrian.  At the 2012 Summer Olympics he competed in the individual eventing.  Ludwig picked up the Shearwater/ERA Rising Star Award 2013 at the Event Riders Association´s annual ball.  The award was given to the rider who impressed the most on the International stage in 2013, and the decision was unanimously agreed up on by the jury!  At the CCI4* Badminton Horse Trials, Svennerstål with his horse Alexander IV, made a super performance around the cross country, but due to an injury the combination had to withdraw before the Show Jumping phase.  At the European Championships in Malmö, Sweden, Svennerstål saddled up last year´s Olympic ride Shamwari 4, and the combination had their hands on an individual medal, but after two poles came flying down during the final phase of show jumping they had to "settle" for a team silver for Sweden.  At the Land Rover Burghley Horse Trials, King Bob, made an over all super performance which led to a final ninth placing.

Stefano Brecciaroli: Stefano Brecciaroli (born 17 November 1974 in Rome, Italy) is an Italian Olympic eventing rider.  He competed at four Summer Olympics (in 2004, 2008, 2012 Summer Olympics and 2016.  He best finished 5th in team eventing at the 2008 Olympics.  Meanwhile, his current best individual Olympic placement is 19th position from 2012.

Rafalca: Rafalca is a dressage horse co-owned by Ann Romney that performed in the equestrian competition at the 2012 Summer Olympics, with rider (and co-owner/trainer) Jan Ebeling.

Ann Romney: Ann Lois Romney (née Davies; born April 16, 1949) is the wife of American businessman and politician, Mitt Romney.  From 2003 to 2007, Romney was First Lady of Massachusetts, while her husband served as Governor.

Minna Telde: Minna Telde (born 1974) is a Swedish horse rider.  She was born in Uppsala.  She competed at the 2004 Summer Olympics in Athens.  She also represented Sweden in individual dressage and team dressage at the 2012 Summer Olympics in London.

Supporting paragraphs: Rafalca Ann Romney
Answer: Jan Ebeling