Question: The 2015 Bahrain GP2 Series' first race was won by a driver who hailed from what country?

Context paragraphs:
2014 Bahrain GP2 Series round: The 2014 Bahrain GP2 Series round was a pair of motor races held on 6 and 7 April 2014 at the Bahrain International Circuit in Sakhir, Bahrain as part of the GP2 Series.  It was the first round of the 2014 GP2 Series and was run in support of the 2014 Bahrain Grand Prix.  The first race, a 32-lap feature event, was won by ART Grand Prix driver Stoffel Vandoorne after starting from second position.  Julián Leal finished second for the Carlin team and DAMS driver Jolyon Palmer came in third.  Palmer won the second race, a 23-lap sprint event, ahead of Rapax driver Simon Trummer in second and Leal third.

2005 Bahrain GP2 Series round: The 2005 Bahrain GP2 Series round was a GP2 Series motor race held on September 29 and 30, 2005 at the Bahrain International Circuit in Sakhir, Bahrain.  It was the final round of the 2005 GP2 Series season.  The race weekend was a stand-alone event unlike the previous GP2 rounds which support Formula One Grands Prix.

Dallara GP2/11: The Dallara GP2/11 is a racing car developed by Italian manufacturer Dallara for use in the FIA Formula 2 Championship, a feeder series for Formula One.  The GP2/11 is the overall third generation of car used by the GP2 Series and first generation of car used by the FIA Formula 2 Championship, and was introduced at the Yas Marina round of the 2011 season, replacing the Dallara GP2/08, which was also developed by Dallara.  The GP2/11 was scheduled to be used until the end of the 2013 season, in keeping with the series' philosophy of upgrading its chassis every three years, but series organisers decided to keep it in competition for another three-year cycle in a bid to cut costs in the category and to be used until the end of the 2016 season until the next-generation car introduced in 2017 season.  But due to another cost-cutting, GP2 Series announced Dallara GP2/11 will extend their service until the end of 2017 season and thus the next-generation car introduced in 2018 season.  As the GP2 Series is a spec series, the GP2/11 is raced by every team and driver on the grid.  Dallara GP2/11 scheduled to retire from competition after 2017 Yas Marina Formula 2 round.

2013 Bahrain GP2 Series round: The 2013 Bahrain GP2 Series round is a pair of motor races held on March 23 and 24, 2013 at Sepang International Circuit, Malaysia as part of the GP2 Series.  It is the second round of the 2013 season.  The race weekend supported the 2013 Bahrain Grand Prix.

2015 Monaco GP2 Series round: The 2015 Monaco GP2 Series round was a pair of motor races held on 22 and 23 May 2015 at the Circuit de Monaco, Monte Carlo, Monaco as part of the GP2 Series.  It was the third round of the 2015 GP2 season and was run in support of the 2015 Monaco Grand Prix.  The first race, a 40-lap feature event, was won by ART Grand Prix driver Stoffel Vandoorne who started from fourth position.  Alexander Rossi finished second for Racing Engineering, and MP Motorsport driver Sergio Canamasas came in third.  Status Grand Prix driver Richie Stanaway won the second event, a 30-lap sprint race, ahead of Trident's Raffaele Marciello and Sergey Sirotkin of the Rapax team.

Stoffel Vandoorne: Stoffel Vandoorne (born 26 March 1992) is a professional racing driver from Belgium, currently competing in Formula 1.  Vandoorne is contracted to a full-time 2017 McLaren race seat, replacing the outgoing Jenson Button. .  Vandoorne is currently residing in both Monte-Carlo (Monaco) and Roeselare (Belgium).

2013 Monaco GP2 Series round: The 2013 Monaco GP2 Series round was a pair of motor races held on 24 and 25 May 2013 at the Circuit de Monaco, Monte Carlo, Monaco as part of the GP2 Series.  It was the fourth round of the 2013 GP2 Series and was run in support of the 2013 Monaco Grand Prix.  The first race, a 42-lap feature event, was won by Russian Time driver Sam Bird after starting from third position.  Kevin Ceccon finished second for the Trident Racing team and Arden International driver Mitch Evans came in third.  Stefano Coletti of the Rapax team won the second event, a 30-lap sprint race, ahead of MP Motorsport's Adrian Quaife-Hobbs in second and Evans third.

2016 Baku GP2 Series round: The 2016 Baku GP2 Series round was a pair of motor races held on 18 and 19 June 2016 at the Baku City Circuit in Azerbaijan as part of the GP2 Series.  It was the third round of the 2016 GP2 Series and was run in support of the 2016 European Grand Prix.  The first race, a 26-lap feature event, was won by Prema Racing driver Antonio Giovinazzi who started from pole position.  Sergey Sirotkin finished second for ART Grand Prix, and Russian Time driver Raffaele Marciello came in third.  Giovinazzi won the second event, a 21-lap sprint race, ahead of teammate Pierre Gasly in second and Sirotkin in third.

2012 Bahrain GP2 Series rounds: The 2012 Bahrain GP2 Series rounds were a series of GP2 Series motor races held at the Bahrain International Circuit as part of the 2012 GP2 Series season.  The first round was held on 21 and 22 April, in support of the 2012 Bahrain Grand Prix.  The second round was held one week later as an independent round of the championship, the only one of its kind on the 2012 calendar.

2015 Bahrain GP2 Series round: The 2015 Bahrain GP2 Series round was a pair of motor races held on 18 and 19 April 2015 at the Bahrain International Circuit in Sakhir, Bahrain as part of the GP2 Series.  It was the first round of the 2015 GP2 Series and was run in support of the 2015 Bahrain Grand Prix.  The first race, a 32-lap feature event, was won by ART Grand Prix driver Stoffel Vandoorne who started from the pole position.  Rio Haryanto finished second for the Campos Racing team, and Racing Engineering driver Alexander Rossi came third.  Haryanto won the second event, a 23-lap sprint race, ahead of Vandoorne in second, and Lazarus driver Nathanaël Berthon in third.

Supporting paragraphs: 2015 Bahrain GP2 Series round Stoffel Vandoorne
Answer: Belgium