Question: Which former captain of the Pakistani side was bought under the contract for the fourth season of the Chittagong Vikings?

Context articles: 2015–16 Bangladesh Premier League
Shoaib Malik
List of Chittagong Vikings cricketers
Taskin Ahmed
Mohammad Salahuddin
Chittagong Division cricket team
Chittagong Vikings in 2016
Chittagong Vikings
Shahidul Islam (cricketer, born 1995)
Ravi Bopara

The 2015-16 Bangladesh Premier League, abbreviated as BPL 3 and BRB BPL 2015, was the third season of the Bangladesh Premier League (BPL), a twenty20 cricket league established by the Bangladesh Cricket Board in 2012.
 The tournament featured six teams during the third season.
 The season began on Friday, 20 November 2015, with a lavish opening ceremony held at Sher-e-Bangla National Cricket Stadium in Dhaka, and the annual kickoff game was held between Chittagong Vikings and Rangpur Riders, which resulted with the Rangpur winning by two wickets in last ball finish.
Shoaib Malik (Punjabi, Urdu: ‎ ; born 1 February 1982) is a Pakistani cricketer and former captain of the Pakistani side.
 He made his One-Day International debut in 1999 against the West Indies and his Test debut in 2001 against Bangladesh.
 On 3 November 2015, he announced his retirement from Test cricket and says his focus is to play in the 2019 Cricket World Cup.
This is presenting a complete list in alphabetical order of cricketers who have played for Chittagong Vikings in Twenty20 matches held by the Bangladesh Premier League.
 The Chittagong Vikings franchise was formed ahead of the 2015 BPL edition, replacing the former Chittagong Kings team which participated in the 2012 and 2013 BPL editions.
 The list includes all players who represented the Kings.
 Complying with other club lists, details are the player's name followed by his years active as a Chittagong Kings/Vikings player, current players to the end of the 2015–16 Bangladeshi cricket season.
Taskin Ahmed Tazim (born 3 April 1995) is a Bangladeshi cricketer.
 He is the son of businessman Abdur Rashid and Sabina Yasmin.
 He is a right-arm fast bowler and a left-handed batsman.
 He represents Dhaka Metropolis in first-class and List A cricket and the Chittagong Kings and Chittagong Vikings franchise in the Bangladesh Premier League.
Mohammad Salahuddin is a Bangladeshi cricket coach.
 He is an experienced coach at the domestic level; coaching Sylhet Royals, Comilla Victorians, Chittagong Vikings and more teams in the past.
 He also acts as an advisor to Shakib Al Hasan.
 He will coach the Victorians once again.
Chittagong Division cricket team represents the Chittagong Division, one of the seven administrative regions in Bangladesh.
 The team was founded in 1999 to compete in the National Cricket League (NCL) and plays first-class cricket.
 For the short-lived National Cricket League Twenty20 in 2010, the team adopted the name Cyclones of Chittagong (often abbreviated as CC).
 The equivalent team in the Bangladesh Premier League is the Chittagong Vikings (qv), replacing the Chittagong Kings.
The Chittagong Vikings are a franchise cricket team based in Chittagong, Bangladesh, which plays in the Bangladesh Premier League (BPL).
 They are one of the seven teams that are competing in the 2016 Bangladesh Premier League.
 The team is being captained by Tamim Iqbal.
 The Vikings returned to the 4th season of the league, only retaining three players from the previous season.
 Tamim Iqbal will continue as the captain of the team, with a drastic change in the management.
 Due to failure in previous season, contract of Marvan Atapattu was not renewed, and Mohammad Salahuddin was appointed as the coach, who coached defending champions Comilla Victorians last season.
 Chris Gayle, Dwayne Smith, Shoaib Malik and Grant Elliott were bought under the contract for the fourth season.
The Chittagong Vikings (Bengali: চট্রগ্রাম ভাইকিংস্ ) are a franchise cricket team which participates in the Bangladesh Premier League
Shahidul Islam (born 5 January 1995) is a Bangladeshi first-class cricketer who plays for Dhaka Metropolis.
 He made his Twenty20 (T20) debut on 21 November 2016 playing for Chittagong Vikings in the 2016–17 Bangladesh Premier League.
Ravinder Singh "Ravi" Bopara (born 4 May 1985) is an English cricketer who plays for Essex and England.
 Originally a top-order batsman, his developing medium pace bowling has made him an all-rounder and he has the best bowling figures for England in a Twenty20 International.
 Bopara has also played for Kings XI Punjab in the Indian Premier League, Chittagong Vikings in the Bangladesh Premier League, Sydney Sixers in the Big Bash League and Karachi Kings in the Pakistan Super league.