Question: Who is the maternal grandfather of Bianca Riario?

Knowledge 1: Bianca Riario
Bianca Riario (March 1478 – 1522) was an Italian noble and regent, Marchioness of San Secondo by marriage to Troilo I de' Rossi, and regent of the marquisate and county of San Secondo for her son Pier Maria during his minority between 1521 and 1522.She was the eldest child and only daughter of Caterina Sforza by the latter's first husband, Girolamo Riario, a nephew of Pope Sixtus IV.Bianca married twice; her first husband was Astorre III Manfredi, Lord of Faenza, and her second husband, Troilo I de' Rossi, 1st Marquis of San Secondo, 6th Count of San Secondo, by whom she had eight recorded children.At the time, the de' Rossi was one of the most prestigious noble families in Parma.Bianca was the half-sister of the celebrated condottiero Giovanni delle Bande Nere, to whom she acted as a substitute mother while their own mother, Caterina was held prisoner by Cesare Borgia. [SEP] Knowledge 2: Caterina Sforza
Caterina Sforza (1463 – 28 May 1509) was an Italian noblewoman along with the Countess of Forlì and Lady of Imola, firstly with her husband Girolamo Riario, and after his death as a regent of her son Ottaviano.Caterina was the illegitimate daughter of Galeazzo Maria Sforza, Duke of Milan and Lucrezia, the wife of the courtier Gian Piero Landriani, a close friend of the Duke.She was raised in the refined Milanese court.The descendant of a dynasty of noted condottieri, from an early age, Caterina distinguished herself through her bold and impetuous actions taken to safeguard her possessions from possible usurpers and to defend her dominions from attack, when they were involved in political intrigues.In her private life Caterina was devoted to various activities, including experiments in alchemy and a love of hunting and dancing.She had many children, butonly the youngest, Captain Giovanni dalle Bande Nere, inherited his mother's forceful, militant personality.Caterina's resistance to Cesare Borgia meant she had to face his fury and imprisonment.Once she gained her freedom in Rome, she led a quiet life in Florence.In the final years of her life, she confided to a monk: "Se io potessi scrivere tutto, farei stupireil mondoIfI could write everything that happened, I would shock the world").
Knowledge 1: Bianca Riario
Bianca Riario (March 1478 – 1522) was an Italian noble and regent, Marchioness of San Secondo by marriage to Troilo I de' Rossi, and regent of the marquisate and county of San Secondo for her son Pier Maria during his minority between 1521 and 1522.She was the eldest child and only daughter of Caterina Sforza by the latter's first husband, Girolamo Riario, a nephew of Pope Sixtus IV.Bianca married twice; her first husband was Astorre III Manfredi, Lord of Faenza, and her second husband, Troilo I de' Rossi, 1st Marquis of San Secondo, 6th Count of San Secondo, by whom she had eight recorded children.At the time, the de' Rossi was one of the most prestigious noble families in Parma.Bianca was the half-sister of the celebrated condottiero Giovanni delle Bande Nere, to whom she acted as a substitute mother while their own mother, Caterina was held prisoner by Cesare Borgia. [SEP] Knowledge 2: Fujiwara no Nagara
, also known as Fujiwara no Nagayoshi, was a Japanese statesman, courtier and politician of the early Heian period.He was the grandfather of Emperor Yōzei.
Knowledge 1: Bianca Riario
Bianca Riario (March 1478 – 1522) was an Italian noble and regent, Marchioness of San Secondo by marriage to Troilo I de' Rossi, and regent of the marquisate and county of San Secondo for her son Pier Maria during his minority between 1521 and 1522.She was the eldest child and only daughter of Caterina Sforza by the latter's first husband, Girolamo Riario, a nephew of Pope Sixtus IV.Bianca married twice; her first husband was Astorre III Manfredi, Lord of Faenza, and her second husband, Troilo I de' Rossi, 1st Marquis of San Secondo, 6th Count of San Secondo, by whom she had eight recorded children.At the time, the de' Rossi was one of the most prestigious noble families in Parma.Bianca was the half-sister of the celebrated condottiero Giovanni delle Bande Nere, to whom she acted as a substitute mother while their own mother, Caterina was held prisoner by Cesare Borgia. [SEP] Knowledge 2: Kaya Alp
Kaya Alp was, according to Ottoman tradition, the son of Kızıl Buğa and the father of Suleyman Shah, who was, in turn, the grandfather of Ertuğrul, and the great grandfather of the Ottoman Empire founder, Osman I.

Answer: Galeazzo Maria Sforza