Question: What type of tennis do Mark Knowles and Andy Ram specialize in?

Context paragraphs:
Mark Knowles: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis.  He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor.  At various times between 2002 and 2005 he was ranked World No. 1 in doubles.  He is a five-time Olympian.

2013 SAP Open – Doubles: Mark Knowles and Xavier Malisse were the defending champions but Knowles did not participate this year because of his retirement from professional tennis in September 2012. <br>

2002 Canada Masters – Doubles: The 2002 Canada Masters – Doubles was the men's singles event of the one hundred and thirteenth edition of the Canada Masters; a WTA Tier I tournament and the most prestigious men's tennis tournament held in Canada.  Jiří Novák and David Rikl were the defending champions but they competed with different partners that year, Novák with Radek Štěpánek and Rikl with David Prinosil.  Novak and Štěpánek lost in the second round to Mark Knowles and Daniel Nestor.  Prinosil and Rikl lost in the semifinals to Bob Bryan and Mike Bryan.  The Bryans won in the final 4–6, 7–6, 6–3 against Knowles and Nestor.

Bartolomé Salvá Vidal: Bartolomé "Tomeu" Salvá Vidal (born November 20, 1986 in Majorca, Balearic Islands) is a Spanish tennis player.  While he plays singles, he is also a doubles player, who partners with friend Rafael Nadal.  In 2007 at the Open Seat Open in Barcelona, Spain, Salvá and Nadal made it to the final (on red clay, the surface that Nadal excels on), defeating Jonathan Erlich and Andy Ram (both ranked 13) and Mark Knowles and Daniel Nestor (both ranked fifth) in straight sets on both occasions.  They made it to the finals, but Alexander Waske and Andrei Pavel defeated them 6–3, 7–6 (1).

David Sherwood: David Sherwood is a tennis coach and former British tennis player.  In his only live Davis Cup match, Sherwood played doubles with Andy Murray beating the Israeli World No 4 doubles team of Jonathan Erlich and Andy Ram,

2009 Australian Open – Men's Doubles: Jonathan Erlich and Andy Ram were the defending champions, but Erlich chose not to participate due to an elbow injury, and only Ram competed that year.Ram partnered with Max Mirnyi, but lost to Feliciano López and Fernando Verdasco in the second round.

2008 Stella Artois Championships – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Knowles chose not to participate, and only Nestor competed that year.

2011 SAP Open – Doubles: Mardy Fish and Sam Querrey were the defending champions, but Fish chose not to compete.Querrey decided to play with Juan Martín del Potro, but lost in the quarterfinals to Mark Knowles and Michal Mertiňák. <br>Scott Lipsky and Rajeev Ram won in the final, 6–4, 4–6, [10–8], against Alejandro Falla and Xavier Malisse.

Andy Ram: Andy Ram (Hebrew: אנדי רם‎ ‎ ; born April 10, 1980) is a retired Israeli professional tennis player.  He is primarily a doubles player.

2009 BNP Paribas Open – Men's Doubles: Jonathan Erlich and Andy Ram were the defending champions, but Erlich chose not to participate due to injury, and only Ram competed that year.Ram partnered with Max Mirnyi, they lost in the final to Mardy Fish and Andy Roddick 6–3, 1–6, [12–14]

Supporting paragraphs: Mark Knowles Andy Ram
Answer: doubles