Question: Who is the paternal grandfather of Duke Xuan Of Qin?

Knowledge 1: Duke Xuan of Qin
Duke Xuan of Qin (died 664 BC) was from 675 to 664 BC the twelfth ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke Xuan was his posthumous title.Duke Xuan was the eldest of the three sons of his father Duke De of Qin, and succeeded his father as ruler of Qin when Duke De died in 676 BC, aged 34.He reigned for 12 years and died in 664 BC.Although Duke Xuan had nine sons, he passed the throne to his younger brother Duke Cheng of Qin, who would in turn pass the throne to the third brother Duke Mu of Qin. [SEP] Knowledge 2: Duke De of Qin
Duke De of Qin (710–676 BC) was from 677 to 676 BC the eleventh ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke De was his posthumous title.Duke De was the second of the three sons of his father Duke Xian of Qin.His younger half-brother Chuzi was the first to succeed Duke Xian in 704 BC, but was killed six years later.His older brother Duke Wu of Qin then ascended the throne and reigned for 20 years.Although Duke Wu had a son named Bai (白), when he died in 678 BC it was Duke De who succeeded him, while Prince Bai was enfeoffed at the capital Pingyang.In the first year of his reign, Duke De moved the capital to Yong (in present-day Fengxiang, Shaanxi), which would remain the capital of Qin until almost three centuries later, when Duke Xian (Shixi) moved the capital to Yueyang (櫟陽) in 383 BC.However, Duke De reigned for only two years before dying in 676 BC, aged 34.He had three sons, who would in turn ascend the throne as Duke Xuan, Duke Cheng, and Duke Mu, respectively.
Knowledge 1: Duke Xuan of Qin
Duke Xuan of Qin (died 664 BC) was from 675 to 664 BC the twelfth ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke Xuan was his posthumous title.Duke Xuan was the eldest of the three sons of his father Duke De of Qin, and succeeded his father as ruler of Qin when Duke De died in 676 BC, aged 34.He reigned for 12 years and died in 664 BC.Although Duke Xuan had nine sons, he passed the throne to his younger brother Duke Cheng of Qin, who would in turn pass the throne to the third brother Duke Mu of Qin. [SEP] Knowledge 2: Duke Cheng of Qin
Duke Cheng of Qin (died 660 BC) was from 663 to 660 BC the thirteenth ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke Cheng was his posthumous title.Duke Cheng was the second of the three sons of his father Duke De of Qin.His older brother Duke Xuan of Qin succeeded his father as ruler of Qin in 676 BC.But when Duke Xuan died in 664 BC, he passed the throne to Duke Cheng instead of one of his nine sons.When Duke Cheng died four years later, he did the same and passed the throne to the third brother Duke Mu of Qin, even though he had seven sons.
Knowledge 1: Duke De of Qin
Duke De of Qin (710–676 BC) was from 677 to 676 BC the eleventh ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke De was his posthumous title.Duke De was the second of the three sons of his father Duke Xian of Qin.His younger half-brother Chuzi was the first to succeed Duke Xian in 704 BC, but was killed six years later.His older brother Duke Wu of Qin then ascended the throne and reigned for 20 years.Although Duke Wu had a son named Bai (白), when he died in 678 BC it was Duke De who succeeded him, while Prince Bai was enfeoffed at the capital Pingyang.In the first year of his reign, Duke De moved the capital to Yong (in present-day Fengxiang, Shaanxi), which would remain the capital of Qin until almost three centuries later, when Duke Xian (Shixi) moved the capital to Yueyang (櫟陽) in 383 BC.However, Duke De reigned for only two years before dying in 676 BC, aged 34.He had three sons, who would in turn ascend the throne as Duke Xuan, Duke Cheng, and Duke Mu, respectively. [SEP] Knowledge 2: Duke Cheng of Qin
Duke Cheng of Qin (died 660 BC) was from 663 to 660 BC the thirteenth ruler of the Zhou Dynasty state of Qin that eventually united China to become the Qin Dynasty.His ancestral name was Ying , and Duke Cheng was his posthumous title.Duke Cheng was the second of the three sons of his father Duke De of Qin.His older brother Duke Xuan of Qin succeeded his father as ruler of Qin in 676 BC.But when Duke Xuan died in 664 BC, he passed the throne to Duke Cheng instead of one of his nine sons.When Duke Cheng died four years later, he did the same and passed the throne to the third brother Duke Mu of Qin, even though he had seven sons.

Answer: Duke Xian of Qin