Question: Which tennis player has a higher World singles ranking, Fred McNair or Kim Warwick?
Context: The Aptos Open is a defunct tennis tournament that was played on the Grand Prix tennis circuit in 1973.  The event was held in Aptos, California and was played on outdoor hard courts.  Jeff Austin won the singles title while Jeff Austin and Fred McNair partnered to win the doubles title. Roscoe Tanner (born October 15, 1951) is a retired American professional tennis player, who turned pro in 1972 and reached a career-high world singles ranking of World No. 4 on July 30, 1979. Frederick V. McNair IV (born July 22, 1950 in Washington, D.C.) is a former professional tennis player from the United States who reached the World No. 1 doubles ranking in 1976.  That year, he teamed up with Sherwood Stewart to capture the men's doubles titles at French Open, the German Open and the Masters.  McNair was also a mixed doubles runner-up at the French Open in 1981, partnering Betty Stöve.  In 1978, he was a member of the US team that won the Davis Cup.  In nine years on the professional tour, McNair won 16 doubles titles.  His career-high singles ranking was World No. 67. This is a list of the main career statistics of Australian former tennis player Evonne Goolagong.  During her career, which lasted from 1967 to 1983, Goolagong won seven singles titles at a Grand Slam event and was a runner-up on 11 occasions.  In addition she won five Grand Slam doubles titles, partnering Margaret Court, Peggy Michel and Helen Gourlay, as well as one mixed doubles title with Kim Warwick.  In total she won 82 singles titles, 46 doubles titles and 4 mixed doubles titles.  She achieved a No. 1 singles ranking for a two-week period in April–May 1976 although this was only officially recognized in 2007.  She was a member of the Australian Federation Cup teams that won the cup in 1971, 1973 and 1974. Vasek Pospisil (, ] ; born June 23, 1990) is a Canadian professional tennis player.  He is the No. 3 male ranked player in Canada, after Milos Raonic and Denis Shapovalov.  Pospisil has a career-high World singles ranking of 25, and No. 4 in doubles.  As Canada's currently ranked No. 3 in singles and No. 3 in doubles, he is an important member of the Canada Davis Cup team.  Along with partner Jack Sock, he won the 2014 Wimbledon Championships and the 2015 Indian Wells Masters men's doubles titles.  He also reached the quarterfinals in singles at the 2015 Wimbledon Championships. Hans Simonsson (born 1 May 1962 in Färgaryd) is a retired professional tennis player from Sweden.  Primarily a doubles specialist, he won 12 ATP Tour titles in his career.  He won the French Open doubles title in 1983 with his countryman Anders Järryd.  He also played in the 1983 Davis Cup final for Sweden.  He reached his career high doubles ranking of No. 10 in the world on 2 January 1984.  Simonsson again reached the French Open doubles final in 1985, but he and Schlomo Glickstein were defeated by Mark Edmondson and Kim Warwick.  The Swede finished his career prematurely at the age of 25.  He's the brother of Stefan Simonsson. Jim Thomas (born September 24, 1974) is an American former professional tennis player.  His highest ATP world singles ranking was number 288, which he reached on November 2, 1998.  His career high in doubles was at 29, set on August 21, 2006.  He retired following the 2008 season. Kim Warwick (born 8 April 1952) is an Australian former professional male tennis player who competed on the ATP Tour from 1970–1987 reaching the final of the singles Australian Open in 1980.  He defeated over 35 players ranked in the top 10 including Guillermo Vilas, Raul Ramerez, Vitas Gerulaitis, Jan Kodeš, Bob Lutz and Arthur Ashe.  Warwick's career-high singles ranking was World No. 15, achieved in 1981.  He won three singles titles and 26 doubles, including Australian Open 1978 (with Wojtek Fibak) and Australian Open 1980 and 1981, Roland Garros 1986 and also a runner-up in Australian Open 1985, all of them partnering fellow countryman Mark Edmondson.  Partnering with Evonne Goolagong, he won the French Open 1972, defeating Françoise Dürr and Jean-Claude Barclay in the final 6–2, 6–4.  Evonne and Kim were finalists in 1972 at Wimbledon against Rosie Casals and Ilie Năstase who won 6–4, 6–4. Dimitar Kuzmanov (Bulgarian: Димитър Кузманов , ] ; nickname: Miko; born 28 July 1993) is a Bulgarian professional tennis player and the current No. 3 Bulgarian in the ATP singles ranking.  His highest singles ranking was No. 281 (8 February 2016), whilst his best doubles ranking was No. 445 (8 February 2016).  Kuzmanov is a player of Tennis Club Lokomotiv Plovdiv and is coached by former Bulgarian tennis player Stefan Rangelov and by Bulgaria Fed Cup team's former tennis player and present captain Dora Rangelova.  In 2011 he was invited to play for Bulgaria Davis Cup team. Ernests Gulbis (] , born 30 August 1988, and nicknamed "The Gull" or "Ernie") is a Latvian professional tennis player.  In 2008, Gulbis won his first ATP Tour doubles title at the U.S. Men's Clay Court Championships, teaming with Rainer Schüttler, and in 2010 won his first ATP Tour singles title in the Delray Beach, defeating Ivo Karlović in the final.  In total, Gulbis has 6 ATP titles to his name and has never lost a final.  His best performance at a Grand Slam is reaching the semifinals of the 2014 French Open.  He had previously reached the quarterfinals of the 2008 French Open.  Gulbis' career-high singles ranking is world No. 10, making him the only Latvian tennis player ever to be ranked inside the top 10 in ATP Singles Ranking.  He achieved this in June 2014.
Answer: Kim Warwick