Question: Wistful, an American racehorse, won at which Louisville, Kentucky Grade 1 stakes race?

Context paragraphs:
Miss Oceana: Miss Oceana (1981–1988) was an American Thoroughbred racehorse who won six Grade 1 stakes during her racing career and was sold for a World Record price as a broodmare.

Palace Music (horse): Palace Music (April 12, 1981 – January 7, 2008) was an American Thoroughbred racehorse and a Champion sire who won Group/Grade 1 stakes in both Europe and the United States.

Wistful (horse): Wistful (foaled in 1946 in Kentucky) was an American Thoroughbred racehorse.  The daughter of Sun Again and granddaughter of Sun Teddy is best remembered for wins in the Kentucky Oaks, the Coaching Club American Oaks, the Black-Eyed Susan Stakes at Pimlico Race Course.  In 1949, she was voted by the country's top sports writers as the American Champion Three-Year-Old Filly.

Dixie Stakes: The Dixie Stakes is an American Thoroughbred horse race held annually in mid-May at Pimlico Race Course in Baltimore, Maryland.  Frequently referred to as the Dixie Handicap, it is the eighth-oldest graded stakes race in the United States and the oldest stakes race in Maryland and all of the Mid-Atlantic states.  The race is open to horses age three and up and is run one and one-eighth miles on the turf.  Currently a Grade II stakes race with a purse of $250,000, at one time the Dixie was a very important race that drew the top horses from across North America.

Rachel Alexandra: Rachel Alexandra (foaled January 29, 2006 in Kentucky) is a retired American Thoroughbred racehorse and the 2009 Horse of the Year.  When she won the 2009 Preakness Stakes, the second leg of the Triple Crown, she became the first filly to win the race in 85 years (the last filly to win was Nellie Morse, in 1924).  She also won races in six states (KY, LA, AR, MD, NY, NJ), on eight different tracks, against fillies and Grade 1 colts and older horses, achieving a long string of consecutive wins including numerous Grade 1 stakes.  Rachel Alexandra neared or broke multiple stakes records, track records and winning margin records throughout her career.  On September 28, 2010, owner Jess Jackson announced Rachel Alexandra's retirement.  She was bred to 2007/2008 Horse of the Year Curlin and delivered a colt on January 22, 2012.

Got Koko: Got Koko (foaled January 25, 1999 in Texas, died 2009) was an American Thoroughbred racehorse, one of only three horses bred in the State of Texas to ever win a Grade 1 stakes.  She was bred by Eileen H. Hartis who sold her for $30,000 at the 2000 Keeneland September yearling sale to trainer Bruce Headley who sold a twenty-five percent interest in the filly to Paul Leung for $25,000.

Harlan's Holiday: Harlan's Holiday (April 6, 1999 – November 1, 2013) was an American Thoroughbred racehorse who won three Grade 1 stakes before retiring to stud where he has become a successful sire.

Kentucky Oaks: The Kentucky Oaks is a Grade I stakes race for three-year-old Thoroughbred fillies staged annually in Louisville, Kentucky, United States.  The race currently covers 1+1/8 mi at Churchill Downs; the horses carry 121 lb .  The Kentucky Oaks is held on the Friday before the Kentucky Derby each year.  The winner gets a $600,000 purse and a large garland of lilies, affectionately called the "Lillies for the Fillies."  A silver Kentucky Oaks Trophy is presented to the winner.

Animal Kingdom (horse): Animal Kingdom (foaled in Kentucky on March 20, 2008) is an American Thoroughbred racehorse best known for winning the 137th Kentucky Derby and the 2013 Dubai World Cup.  His Derby win took place on May 7, 2011, before a record crowd of 164,858.  After the Derby, Animal Kingdom finished second in the Preakness Stakes and sixth in the Belmont Stakes before his career was disrupted by injury.  He returned to finish second in the 2012 Breeders' Cup Mile before winning the Dubai World Cup as a five-year-old in 2013.  Animal Kingdom is the first Kentucky Derby winner to win a Grade 1 race at the age of five.  He has won Grade 1 races on both dirt and synthetic surfaces.

Whitney Handicap: The Whitney Stakes (run as a handicap through 2013 and still sometimes referred to as the "Whitney Handicap") is an American Grade 1 stakes race for Thoroughbred racehorses three years of age and older run at a distance of 1 ⁄ miles.  The current purse is $1,250,000.

Supporting paragraphs: Wistful (horse) Kentucky Oaks
Answer: The Kentucky Oaks