premise: Seohyun is 45 years old.
hypothesis: Seo Ju-hyun ( born June 28 , 1991 ) , known professionally as Seohyun , is a South Korean singer and actress . She debuted as a solo artist with her debut mini album , Do n't Say No , on January 17 , 2017 , making her the third Girls ' Generation member to debut as a solo artist .