Detailed Instructions: Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Q: Context: Marquis Xuan of Cai () (? - 715 BC), born Ji Cuofu (), was the eleventh ruler of the State of Cai from 750 BC to 715 BC. He was the only known son of Marquis Dai of Cai (), his predecessor.
Question: Who fathered Marquis Xuan of Cai?
A:
marquis dai of cai