Given a short bio of a person, find the minimal text span containing the date of birth of the person. The output must be the minimal text span that contains the birth date, month and year as long as they are present. For instance, given a bio like 'I was born on 27th of Decemeber 1990, and graduated high school on 23rd October 2008.' the output should be '27th of December 1990'.

[EX Q]: Cook was born in 1903 in San Francisco, California, the son of Elisha Vanslyck Cook Sr
[EX A]: 1903

[EX Q]: Walken was born Ronald Walken on March 31, 1943, in Astoria, Queens, New York, the son of Rosalie Russell (May 16, 1907 – March 26, 2010), a Scottish immigrant from Glasgow, and Paul Wälken (October 5, 1903 – February 23, 2001), a German immigrant from Gelsenkirchen who owned and operated Walken's Bakery in Astoria
[EX A]: March 31, 1943

[EX Q]: Katherine Victoria Litwack was born on June 13, 1986, in Bryn Mawr, Pennsylvania
[EX A]:
June 13, 1986